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  • Models, Molecular  (84)
  • Kinetics  (77)
  • American Association for the Advancement of Science (AAAS)  (158)
  • American Geophysical Union
  • Annual Reviews
  • Periodicals Archive Online (PAO)
  • 1990-1994  (158)
  • 1994  (78)
  • 1990  (80)
Collection
Publisher
  • American Association for the Advancement of Science (AAAS)  (158)
  • American Geophysical Union
  • Annual Reviews
  • Periodicals Archive Online (PAO)
  • Wiley-Blackwell  (9)
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  • 1990-1994  (158)
Year
  • 1
    Publication Date: 1990-08-10
    Description: The stimulation of phospholipase A2 by thrombin and type 2 (P2)-purinergic receptor agonists in Chinese hamster ovary cells is mediated by the G protein Gi. To delineate alpha chain regulatory regions responsible for control of phospholipase A2, chimeric cDNAs were constructed in which different lengths of the alpha subunit of Gs (alpha s) were replaced with the corresponding sequence of the Gi alpha subunit (alpha i2). When a carboxyl-terminal chimera alpha s-i(38), which has the last 38 amino acids of alpha s substituted with the last 36 residues of alpha i2, was expressed in Chinese hamster ovary cells, the receptor-stimulated phospholipase A2 activity was inhibited, although the chimera could still activate adenylyl cyclase. Thus, alpha s-i(38) is an active alpha s, but also a dominant negative alpha i molecule, indicating that the last 36 amino acids of alpha i2 are a critical domain for G protein regulation of phospholipase A2 activity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gupta, S K -- Diez, E -- Heasley, L E -- Osawa, S -- Johnson, G L -- DK37871/DK/NIDDK NIH HHS/ -- GM30324/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Aug 10;249(4969):662-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Basic Sciences, National Jewish Center for Immunology and Respiratory Medicine, Denver, CO 80206.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2166341" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/pharmacology ; Animals ; Arachidonic Acid ; Arachidonic Acids/metabolism ; Cell Line ; Chlorides/pharmacology ; Enzyme Activation ; GTP-Binding Proteins/*genetics/metabolism ; Inositol Phosphates/metabolism ; Kinetics ; Lithium/pharmacology ; Lithium Chloride ; Macromolecular Substances ; *Mutation ; Phospholipases/*metabolism ; Phospholipases A/*metabolism ; Phospholipases A2 ; Receptors, Purinergic/drug effects/*physiology ; Restriction Mapping ; Thrombin/antagonists & inhibitors/*pharmacology ; Transfection
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  • 2
    Publication Date: 1990-08-17
    Description: The transcription factor C/EBP uses a bipartite structural motif to bind DNA. Two protein chains dimerize through a set of amphipathic alpha helices termed the leucine zipper. Highly basic polypeptide regions emerge from the zipper to form a linked set of DNA contact surfaces. In the recently proposed a "scissors grip" model, the paired set of basic regions begin DNA contact at a central point and track in opposite directions along the major groove, forming a molecular clamp around DNA. This model predicts that C/EBP must undertake significant changes in protein conformation as it binds and releases DNA. The basic region of ligand-free C/EBP is highly sensitive to protease digestion. Pronounced resistance to proteolysis occurred when C/EBP associated with its specific DNA substrate. Sequencing of discrete proteolytic fragments showed that prominent sites for proteolysis occur at two junction points predicted by the "scissors grip" model. One junction corresponds to the cleft where the basic regions emerge from the leucine zipper. The other corresponds to a localized nonhelical segment that has been hypothesized to contain an N-cap and facilitate the sharp angulation necessary for the basic region to track continuously in the major groove of DNA.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shuman, J D -- Vinson, C R -- McKnight, S L -- New York, N.Y. -- Science. 1990 Aug 17;249(4970):771-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Research Laboratories, Department of Embryology, Baltimore, MD 21210.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2202050" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; CCAAT-Enhancer-Binding Proteins ; Chromatography, High Pressure Liquid ; DNA/*metabolism ; DNA-Binding Proteins/metabolism ; Kinetics ; Leucine ; Macromolecular Substances ; Models, Molecular ; Molecular Sequence Data ; Nuclear Proteins/*metabolism ; Peptide Fragments/metabolism ; Peptide Hydrolases/*metabolism ; Protein Conformation ; Transcription Factors/*metabolism ; Trypsin/metabolism
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  • 3
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-04-06
    Description: The rate of release of guanine nucleotides from the ras proteins (Ras) is extremely slow in the presence of Mg2+. It seemed likely, therefore that a factor might exist to accelerate the release of guanosine diphosphate (GDP), and hence the exchange of GDP for guanosine triphosphate (GTP). Such a factor has now been discovered in rat brain cytosol. Brain cytosol was found to catalyze, by orders of magnitude, the release of guanine nucleotides from recombinant v-H-Ras protein bound with [alpha-32P]GDP. This effect occurred even in the presence of a large excess of Mg2+, but was destroyed by heat or by incubation of the cytosol for an hour at 37 degrees C in the absence of phosphatase inhibitors. The effect was observed with either v-H-Ras or c-H-Ras, but not with p25rab3A, a small G protein with about 30% similarity to Ras. The effect could not be mimicked by addition of recombinant Ras-GAP or purified GEF, a guanine nucleotide exchange factor involved in the regulation of eukaryotic protein synthesis. By gel filtration chromatography, the factor appears to possess a molecular size between 100,000 and 160,000 daltons. This protein (Ras-guanine nucleotide-releasing factor, or Ras-GRF) may be involved in the activation of p21ras.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wolfman, A -- Macara, I G -- CA 43551/CA/NCI NIH HHS/ -- ES 01247/ES/NIEHS NIH HHS/ -- GM 41220/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Apr 6;248(4951):67-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biophysics, University of Rochester Medical Center, NY 14642.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2181667" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Binding, Competitive ; Brain/metabolism ; Cholic Acids ; Cytosol/*metabolism ; Guanine Nucleotides/*metabolism ; Guanosine 5'-O-(3-Thiotriphosphate) ; Guanosine Diphosphate/*metabolism ; Guanosine Triphosphate/analogs & derivatives/metabolism ; Hot Temperature ; Immunosorbent Techniques ; Kinetics ; Magnesium Chloride/pharmacology ; Molecular Weight ; Proto-Oncogene Proteins/*metabolism ; Proto-Oncogene Proteins p21(ras) ; Rats ; Thionucleotides/metabolism
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  • 4
    Publication Date: 1990-08-24
    Description: The protein Felix was designed de novo to fold into an antiparallel four-helix bundle of specific topology. Its sequence of 79 amino acid residues is not homologous to any known protein sequence, but is "native-like" in that it is nonrepetitive and contains 19 of the 20 naturally occurring amino acids. Felix has been expressed from a synthetic gene cloned in Escherichia coli, and the protein has been purified to homogeneity. Physical characterization of the purified protein indicates that Felix (i) is monomeric in solution, (ii) is predominantly alpha-helical, (iii) contains a designed intramolecular disulfide bond linking the first and fourth helices, and (iv) buries its single tryptophan in an apolar environment and probably in close proximity with the disulfide bond. These physical properties rule out several alternative structures and indicate that Felix indeed folds into approximately the designed three-dimensional structure.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hecht, M H -- Richardson, J S -- Richardson, D C -- Ogden, R C -- New York, N.Y. -- Science. 1990 Aug 24;249(4971):884-91.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, Duke University, Durham, NC 27710.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2392678" target="_blank"〉PubMed〈/a〉
    Keywords: *Amino Acid Sequence ; Base Sequence ; DNA/genetics ; *Models, Chemical ; Models, Molecular ; Molecular Sequence Data ; *Protein Conformation ; Protein Denaturation ; *Proteins ; *Recombinant Proteins
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  • 5
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-07-20
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Carter, D C -- He, X M -- New York, N.Y. -- Science. 1990 Jul 20;249(4966):302-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Space Science Laboratory, NASA Marshall Space Flight Center, Huntsville, AL 35812.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2374930" target="_blank"〉PubMed〈/a〉
    Keywords: Humans ; Models, Molecular ; Protein Conformation ; *Serum Albumin ; X-Ray Diffraction
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  • 6
    Publication Date: 1990-11-30
    Description: Conducting gramicidin channels form predominantly by the transmembrane association of monomers, one from each side of a lipid bilayer. In single-channel experiments in planar bilayers the two gramicidin analogs, [Val1]gramicidin A (gA) and [4,4,4-F3-Val1]gramicidin A (F3gA), form dimeric channels that are structurally equivalent and have characteristically different conductances. When these gramicidins were added asymmetrically, one to each side of a preformed bilayer, the predominant channel type was the hybrid channel, formed between two chemically dissimilar monomers. These channels formed by the association of monomers residing in each half of the membrane. These results also indicate that the hydrophobic gramicidins are surprisingly membrane impermeant, a conclusion that was confirmed in experiments in which gA was added asymmetrically and symmetrically to preformed bilayers.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉O'Connell, A M -- Koeppe, R E 2nd -- Andersen, O S -- GM21342/GM/NIGMS NIH HHS/ -- GM34968/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Nov 30;250(4985):1256-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology and Biophysics, Cornell University Medical College, New York, NY 10021.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1700867" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Cell Membrane Permeability ; Chemistry, Physical ; Electric Conductivity ; Gramicidin/*chemistry/metabolism ; Ion Channels/*chemistry/physiology ; Kinetics ; Lipid Bilayers/*chemistry ; Macromolecular Substances ; Molecular Sequence Data ; Physicochemical Phenomena ; Protein Conformation
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  • 7
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-08-17
    Description: A class of transcriptional regulator proteins bind to DNA at dyad-symmetric sites through a motif consisting of (i) a "leucine zipper" sequence that associates into noncovalent, parallel, alpha-helical dimers and (ii) a covalently connected basic region necessary for binding DNA. The basic regions are predicted to be disordered in the absence of DNA and to form alpha helices when bound to DNA. These helices bind in the major groove forming multiple hydrogen-bonded and van der Waals contacts with the nucleotide bases. To test this model, two peptides were designed that were identical to natural leucine zipper proteins only at positions hypothesized to be critical for dimerization and DNA recognition. The peptides form dimers that bind specifically to DNA with their basic regions in alpha-helical conformations.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉O'Neil, K T -- Hoess, R H -- DeGrado, W F -- New York, N.Y. -- Science. 1990 Aug 17;249(4970):774-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Central Research and Development Department, E.I. du Pont de Nemours & Co., Wilmington, DE 19880-0328.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2389143" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Base Sequence ; Binding Sites ; Chemistry, Physical ; Circular Dichroism ; Computer Simulation ; DNA/*metabolism ; DNA-Binding Proteins/*metabolism ; Hydrogen Bonding ; *Leucine ; Macromolecular Substances ; Models, Molecular ; Molecular Sequence Data ; Physicochemical Phenomena ; Protein Conformation
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  • 8
    Publication Date: 1990-12-07
    Description: A genetic system was developed in Escherichia coli to study leucine zippers with the amino-terminal domain of bacteriophage lambda repressor as a reporter for dimerization. This system was used to analyze the importance of the amino acid side chains at eight positions that form the hydrophobic interface of the leucine zipper dimer from the yeast transcriptional activator, GCN4. When single amino acid substitutions were analyzed, most functional variants contained hydrophobic residues at the dimer interface, while most nonfunctional sequence variants contained strongly polar or helix-breaking residues. In multiple randomization experiments, however, many combinations of hydrophobic residues were found to be nonfunctional, and leucines in the heptad repeat were shown to have a special function in leucine zipper dimerization.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hu, J C -- O'Shea, E K -- Kim, P S -- Sauer, R T -- AI15706/AI/NIAID NIH HHS/ -- GM11117/GM/NIGMS NIH HHS/ -- GM44162/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Dec 7;250(4986):1400-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2147779" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Bacteriophage lambda/*genetics ; DNA-Binding Proteins/*genetics ; Escherichia coli/*genetics ; Fungal Proteins/*genetics ; Genetic Variation ; Leucine Zippers/*genetics ; Models, Molecular ; Molecular Sequence Data ; Mutagenesis, Site-Directed ; Phenotype ; Protein Conformation ; *Protein Kinases ; Random Allocation ; Recombinant Fusion Proteins/metabolism ; *Saccharomyces cerevisiae Proteins ; Transcription Factors/*genetics
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  • 9
    Publication Date: 1990-09-28
    Description: The erbB2 oncogene encodes a 185-kilodalton transmembrane protein whose sequence is similar to the epidermal growth factor receptor (EGFR). A 30-kilodalton factor (gp30) secreted from MDA-MB-231 human breast cancer cells was shown to be a ligand for p185erbB2. An antibody to EGFR abolished the tyrosine phosphorylation induced by EGF and transforming growth factor-alpha (TGF-alpha) but only partially blocked that produced by gp30 in SK-BR-3 breast cancer cells. In two cell lines that overexpress erbB2 but do not expresss EGFR (MDA-MB-453 breast cancer cells and a Chinese hamster ovary cell line that had been transfected with erbB2), phosphorylation of p185erbB2 was induced only by gp30. The gp30 specifically inhibited the growth of cells that overexpressed p185erbB2. An antibody to EGFR had no effect on the inhibition of SK-BR-3 cell colony formation obtained with gp30. Thus, it appeared that gp30 interacted directly with the EGFR and erbB2. Direct binding of gp30 to p185erbB2 was confirmed by binding competition experiments, where gp30 was found to displace the p185erbB2 binding of a specific antibody to p185erbB2. The evidence described here suggests that gp30 is a ligand for p185erbB2.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lupu, R -- Colomer, R -- Zugmaier, G -- Sarup, J -- Shepard, M -- Slamon, D -- Lippman, M E -- New York, N.Y. -- Science. 1990 Sep 28;249(4976):1552-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Vincent T. Lombardi Cancer Research Center, Georgetown University Medical Center, Washington, DC 20007.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2218496" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antibodies, Monoclonal ; Binding, Competitive ; Breast Neoplasms ; Cell Line ; Chromatography, Affinity ; Female ; Humans ; Kinetics ; Ligands ; Molecular Weight ; Phosphorylation ; Protein-Tyrosine Kinases/metabolism ; Proto-Oncogene Proteins/genetics/immunology/*metabolism ; Proto-Oncogenes ; Receptor, Epidermal Growth Factor/isolation & purification/*metabolism ; Transfection
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  • 10
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-05-04
    Description: The amino acid sequences of three fragments of cyanogen bromide-digested human placental inositol 1,2-cyclic phosphate 2-phosphohydrolase, an enzyme of the phosphatidylinositol signaling pathway, are identical to sequences within lipocortin III, a member of a family of homologous calcium- and phospholipid-binding proteins that do not have defined physiological functions. Lipocortin III has also been previously identified as placental anticoagulant protein III (PAP III) and calcimedin 35 alpha. Antibodies to PAP III detected PAP III and inositol 1,2-cyclic phosphate 2-phosphohydrolase with identical reactivity on immunoblotting. In addition, inositol 1,2-cyclic phosphate 2-phosphohydrolase was stimulated by the same acidic phospholipids that bind lipocortins.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ross, T S -- Tait, J F -- Majerus, P W -- HLBI 14147/HL/NHLBI NIH HHS/ -- HLBI 16634/HL/NHLBI NIH HHS/ -- HLBI 40801/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1990 May 4;248(4955):605-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Internal Medicine, Washington University School of Medicine, St Louis, MO 63110.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2159184" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Annexin A3 ; Annexins ; Calcium-Binding Proteins/*genetics ; Female ; Humans ; Immunoblotting ; Kinetics ; Molecular Sequence Data ; Phosphoric Diester Hydrolases/*genetics/isolation & purification/metabolism ; Placenta/*enzymology ; Pregnancy
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  • 11
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-09-28
    Description: To understand why proteins adopt particular three-dimensional structures, it is important to elucidate the hierarchy of interactions that stabilize the native state. Proteins in partly folded states can be used to dissect protein organizational hierarchies. A partly folded apomyoglobin intermediate has now been characterized structurally by trapping slowly exchanging peptide NH protons and analyzing them by two-dimensional 1H-NMR (nuclear magnetic resonance). Protons in the A, G, and H helix regions are protected from exchange, while protons in the B and E helix regions exchange freely. On the basis of these results and the three-dimensional structure of native myoglobin, a structural model is presented for the partly folded intermediate in which a compact subdomain retains structure while the remainder of the protein is essentially unfolded.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hughson, F M -- Wright, P E -- Baldwin, R L -- DK34909/DK/NIDDK NIH HHS/ -- GM19988/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Sep 28;249(4976):1544-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, Beckman Center, Stanford University School of Medicine, CA 94305.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2218495" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Apoproteins/chemistry/*metabolism ; Hydrogen-Ion Concentration ; Magnetic Resonance Spectroscopy ; Models, Molecular ; Molecular Sequence Data ; Myoglobin/chemistry/*metabolism ; Protein Conformation ; Spectrophotometry, Ultraviolet
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  • 12
    Publication Date: 1990-08-31
    Description: The isocitrate dehydrogenase of Escherichia coli is an example of a ubiquitous class of enzymes that are regulated by covalent modification. In the three-dimensional structure of the enzyme-substrate complex, isocitrate forms a hydrogen bond with Ser113, the site of regulatory phosphorylation. The structures of Asp113 and Glu113 mutants, which mimic the inactivation of the enzyme by phosphorylation, show minimal conformational changes from wild type, as in the phosphorylated enzyme. Calculations based on observed structures suggest that the change in electrostatic potential when a negative charge is introduced either by phosporylation or site-directed mutagenesis is sufficient to inactivate the enzyme. Thus, direct interaction at a ligand binding site is an alternative mechanism to induced conformational changes from an allosteric site in the regulation of protein activity by phosphorylation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hurley, J H -- Dean, A M -- Sohl, J L -- Koshland, D E Jr -- Stroud, R M -- GM 24485/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Aug 31;249(4972):1012-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Biophysics, University of California, San Francisco 94143-0448.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2204109" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Escherichia coli/*enzymology/genetics ; Homeostasis ; Isocitrate Dehydrogenase/genetics/*metabolism ; Models, Molecular ; Molecular Sequence Data ; Phosphorylation ; Protein Conformation
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  • 13
    Publication Date: 1990-08-03
    Description: Comparison of the 2.4 angstrom resolution crystal structures of dimeric clam hemoglobin in the deoxygenated and carbon-monoxide liganded states shows how radically different the structural basis for cooperative oxygen binding is from that operative in mammalian hemoglobins. Heme groups are in direct communication across a novel subunit interface formed by the E and F helices. The conformational changes at this interface that accompany ligand binding are more dramatic at a tertiary level but more subtle at a quaternary level than those in mammalian hemoglobins. These findings suggest a cooperative mechanism that links ligation at one subunit with potentiation of affinity at the second subunit.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Royer, W E Jr -- Hendrickson, W A -- Chiancone, E -- New York, N.Y. -- Science. 1990 Aug 3;249(4968):518-21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2382132" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Carboxyhemoglobin/metabolism ; Hemoglobins/*metabolism ; Ligands ; Macromolecular Substances ; Models, Molecular ; Molecular Sequence Data ; Mollusca ; Protein Conformation
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  • 14
    Publication Date: 1990-09-28
    Description: Heparin-binding growth factor-1 (HBGF-1) is an angiogenic polypeptide mitogen for mesoderm- and neuroectoderm-derived cells in vitro and remains biologically active after truncation of the amino-terminal domain (HBGF-1 alpha) of the HBGF-1 beta precursor. Polymerase chain reaction mutagenesis and prokaryotic expression systems were used to prepare a mutant of HBGF-1 alpha lacking a putative nuclear translocation sequence (amino acid residues 21 to 27; HBGF-1U). Although HBGF-1U retains its ability to bind to heparin, HBGF-1U fails to induce DNA synthesis and cell proliferation at concentrations sufficient to induce intracellular receptor-mediated tyrosine phosphorylation and c-fos expression. Attachment of the nuclear translocation sequence from yeast histone 2B at the amino terminus of HBGF-1U yields a chimeric polypeptide (HBGF-1U2) with mitogenic activity in vitro and indicates that nuclear translocation is important for this biological response.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Imamura, T -- Engleka, K -- Zhan, X -- Tokita, Y -- Forough, R -- Roeder, D -- Jackson, A -- Maier, J A -- Hla, T -- Maciag, T -- HL 32348/HL/NHLBI NIH HHS/ -- HL 35627/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1990 Sep 28;249(4976):1567-70.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Molecular Biology, Jerome H. Holland Laboratory for the Biomedical Sciences, American Red Cross, Rockville, MD 20855.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1699274" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Base Sequence ; Binding, Competitive ; Cattle ; Cell Division/drug effects ; Cell Line ; Cell Nucleus/metabolism ; Cells, Cultured ; DNA Replication/drug effects ; Endothelium, Vascular/drug effects/metabolism ; Fibroblast Growth Factor 1/*genetics/metabolism/pharmacology ; Kinetics ; Mice ; Mitogens/pharmacology ; Molecular Sequence Data ; *Mutation ; Oligonucleotide Probes ; Receptors, Mitogen/metabolism ; Receptors, Vascular Endothelial Growth Factor ; Recombinant Proteins/metabolism/pharmacology ; Transcription, Genetic/drug effects
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  • 15
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-06-29
    Description: Soluble and hydrophobic lipid breakdown products have a variety of important signaling roles in cells. Here sphingoid bases derived in cells from sphingolipid breakdown are shown to have a potent and direct effect in mediating calcium release from intracellular stores. Sphingosine must be enzymically converted within the cell to a product believed to be sphingosine-1-phosphate, which thereafter effects calcium release from a pool including the inositol 1,4,5-trisphosphate-sensitive calcium pool. The sensitivity, molecular specificity, and reversibility of the effect on calcium movements closely parallel sphingoid base-mediated inhibition of protein kinase C. Generation of sphingoid bases in cells may activate a dual signaling pathway involving regulation of calcium and protein kinase C, comparable perhaps to the phosphatidylinositol and calcium signaling pathway.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ghosh, T K -- Bian, J -- Gill, D L -- NS19304/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1990 Jun 29;248(4963):1653-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Chemistry, University of Maryland School of Medicine, Baltimore 21201.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2163543" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Diphosphate/pharmacology ; Animals ; Calcimycin/pharmacology ; Calcium/*metabolism ; Cell Line ; Kinetics ; Phosphoric Monoester Hydrolases/metabolism ; Phosphorylcholine/analogs & derivatives/pharmacology ; Protein Kinase C/metabolism ; Second Messenger Systems/drug effects ; Sphingosine/*analogs & derivatives/*pharmacology ; Thermodynamics
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  • 16
    Publication Date: 1990-07-20
    Description: The crystallographic structure of a recombinant hirudin-thrombin complex has been solved at 2.3 angstrom (A) resolution. Hirudin consists of an NH2-terminal globular domain and a long (39 A) COOH-terminal extended domain. Residues Ile1 to Tyr3 of hirudin form a parallel beta-strand with Ser214 to Glu217 of thrombin with the nitrogen atom of Ile1 making a hydrogen bond with Ser195 O gamma atom of the catalytic site, but the specificity pocket of thrombin is not involved in the interaction. The COOH-terminal segment makes numerous electrostatic interactions with an anion-binding exosite of thrombin, whereas the last five residues are in a helical loop that forms many hydrophobic contacts. In all, 27 of the 65 residues of hirudin have contacts less than 4.0 A with thrombin (10 ion pairs and 23 hydrogen bonds). Such abundant interactions may account for the high affinity and specificity of hirudin.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rydel, T J -- Ravichandran, K G -- Tulinsky, A -- Bode, W -- Huber, R -- Roitsch, C -- Fenton, J W 2nd -- HL13160/HL/NHLBI NIH HHS/ -- HL43229/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1990 Jul 20;249(4966):277-80.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Michigan State University, East Lansing 48824.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2374926" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Hirudins/*metabolism ; Humans ; Models, Molecular ; Molecular Sequence Data ; Protein Binding ; Protein Conformation ; Recombinant Proteins/metabolism ; Thrombin/*metabolism ; X-Ray Diffraction
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  • 17
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-08-10
    Description: A metalloantibody has been constructed with a coordination site for metals in the antigen binding pocket. The Zn(II) binding site from carbonic anhydrase B was used as a model. Three histidine residues have been placed in the light chain complementarity determining regions of a single chain antibody molecule. In contrast to the native protein, the mutant displayed metal-dependent fluorescence-quenching behavior. This response was interpreted as evidence for metal binding in the three-histidine site with relative affinities in the order Cu(II) greater than Zn(II) greater than Cd(II). The presence of metal cofactors in immunoglobulins should facilitate antibody catalysis of redox and hydrolytic reactions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Iverson, B L -- Iverson, S A -- Roberts, V A -- Getzoff, E D -- Tainer, J A -- Benkovic, S J -- Lerner, R A -- F32GM-1204702/GM/NIGMS NIH HHS/ -- IGM 37684/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Aug 10;249(4969):659-62.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, Research Institute of Scripps Clinic, La Jolla, CA 92037.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2116666" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; *Binding Sites, Antibody ; Cadmium ; Carbonic Anhydrases/*immunology ; Copper ; Fluoresceins ; Immunoglobulin Heavy Chains ; Immunoglobulin Light Chains ; Ligands ; *Metals ; Models, Molecular ; Molecular Sequence Data ; Protein Conformation ; Spectrometry, Fluorescence ; Zinc
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  • 18
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-10-12
    Description: Voltage-dependent ion channels are responsible for electrical signaling in neurons and other cells. The main classes of voltage-dependent channels (sodium-, calcium-, and potassium-selective channels) have closely related molecular structures. For one member of this superfamily, the transiently voltage-activated Shaker H4 potassium channel, specific amino acid residues have now been identified that affect channel blockade by the small ion tetraethylammonium, as well as the conduction of ions through the pore. Furthermore, variation at one of these amino acid positions among naturally occurring potassium channels may account for most of their differences in sensitivity to tetraethylammonium.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉MacKinnon, R -- Yellen, G -- GM 43949/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Oct 12;250(4978):276-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cellular and Molecular Physiology, Harvard Medical School, Boston, MA 02115.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2218530" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Electric Conductivity ; Kinetics ; Membrane Potentials/drug effects ; Molecular Sequence Data ; Mutagenesis, Site-Directed ; Oligonucleotide Probes ; Potassium Channels/drug effects/genetics/*physiology ; Tetraethylammonium ; Tetraethylammonium Compounds/*pharmacology
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  • 19
    Publication Date: 1990-02-16
    Description: Sulfonylurea-sensitive adenosine triphosphate (ATP)-regulated potassium (KATP) channels are present in brain cells and play a role in neurosecretion at nerve terminals. KATP channels in substantia nigra, a brain region that shows high sulfonylurea binding, are inactivated by high glucose concentrations and by antidiabetic sulfonylureas and are activated by ATP depletion and anoxia. KATP channel inhibition leads to activation of gamma-aminobutyric acid (GABA) release, whereas KATP channel activation leads to inhibition of GABA release. These channels may be involved in the response of the brain to hyper- and hypoglycemia (in diabetes) and ischemia or anoxia.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Amoroso, S -- Schmid-Antomarchi, H -- Fosset, M -- Lazdunski, M -- New York, N.Y. -- Science. 1990 Feb 16;247(4944):852-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institut de Pharmacologie Moleculaire et Cellulaire, UPR 411 du CNRS, Valbonne, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2305257" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/*physiology ; Animals ; Cell Hypoxia ; Deoxyglucose/pharmacology ; Glucose/metabolism/*pharmacology ; Hypoglycemic Agents/*pharmacology ; In Vitro Techniques ; Kinetics ; Oligomycins/pharmacology ; Potassium/pharmacology ; Potassium Channels/drug effects/*physiology ; Rubidium/metabolism ; Structure-Activity Relationship ; Substantia Nigra/drug effects/*physiology ; gamma-Aminobutyric Acid/*metabolism
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  • 20
    Publication Date: 1990-05-04
    Description: Platelet-derived growth factor (PDGF) stimulates phospholipase C (PLC) activity and the phosphorylation of the gamma isozyme of PLC (PLC-gamma) in vitro and in living cells. The role of PLC-gamma in the phosphoinositide signaling pathway was addressed by examining the effect of overexpression of PLC-gamma on cellular responses to PDGF. Overexpression of PLC-gamma correlated with PDGF-induced tyrosine phosphorylation of PLC-gamma and with PDGF-induced breakdown of phosphatidylinositol 4,5-bisphosphate (PIP2). However, neither bradykinin- nor lysophosphatidic acid-induced phosphoinositide metabolism was enhanced in the transfected cells, suggesting that the G protein-coupled phosphoinositide responses to these ligands are mediated by other PLC isozymes. The enhanced PDGF-induced generation of inositol trisphosphate (IP3) did not enhance intracellular calcium signaling or influence PDGF-induced DNA synthesis. Thus, enzymes other than PLC-gamma may limit PDGF-induced calcium signaling and DNA synthesis. Alternatively, PDGF-induced calcium signaling and DNA synthesis may use biochemical pathways other than phosphoinositide metabolism for signal transduction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Margolis, B -- Zilberstein, A -- Franks, C -- Felder, S -- Kremer, S -- Ullrich, A -- Rhee, S G -- Skorecki, K -- Schlessinger, J -- New York, N.Y. -- Science. 1990 May 4;248(4955):607-10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Rorer Biotechnology, King of Prussia, PA 19406.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2333512" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Calcium/physiology ; Cattle ; Cell Division/*drug effects ; Cells, Cultured ; DNA Replication/drug effects ; Genetic Vectors ; Inositol Phosphates/metabolism ; Isoenzymes/biosynthesis/*genetics/metabolism ; Kinetics ; Mice ; Platelet-Derived Growth Factor/*pharmacology ; Second Messenger Systems/*drug effects ; Transfection ; Type C Phospholipases/biosynthesis/*genetics/metabolism
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  • 21
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-02-16
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Alper, J -- New York, N.Y. -- Science. 1990 Feb 16;247(4944):804-6.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2154848" target="_blank"〉PubMed〈/a〉
    Keywords: Acquired Immunodeficiency Syndrome/drug therapy ; *Antiviral Agents/therapeutic use ; Capsid/ultrastructure ; Common Cold/*drug therapy ; Drug Design ; Humans ; Models, Molecular ; Protein Conformation ; Rhinovirus/ultrastructure ; Software
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  • 22
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-08-17
    Description: An antibody elicited to a distorted N-methyl porphyrin catalyzed metal ion chelation by the planar porphyrin. At fixed Zn2+ and Cu2+ concentrations, the antibody-catalyzed reaction showed saturation kinetics with respect to the substrate mesoporphyrin IX (2) and was inhibited by the hapten, N-methylmesoporphyrin IX (1). The turnover number of 80 hour-1 for antibody-catalyzed metallation of 2 with Zn2+ compares with an estimated value of 800 hour-1 for ferrochelatase. The antibody also catalyzed the insertion of Co2+ and Mn2+ into 2, but it did not catalyze the metallation of protoporphyrin IX (3) or deuteroporphyrin IX (4). The antibody has high affinity for several metalloporphyrins, suggesting an approach to developing antibody-heme catalysts for redox or electron transfer reactions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cochran, A G -- Schultz, P G -- New York, N.Y. -- Science. 1990 Aug 17;249(4970):781-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of California, Berkeley 94720.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2389144" target="_blank"〉PubMed〈/a〉
    Keywords: Antibodies/*metabolism ; Antigens/immunology ; Catalysis ; Cobalt/metabolism ; Copper/metabolism ; Ferrochelatase/metabolism ; Kinetics ; Manganese/metabolism ; Mesoporphyrins/immunology/metabolism ; Metals/*metabolism ; Porphyrins/*metabolism ; Zinc/metabolism
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  • 23
    Publication Date: 1990-08-13
    Description: The three-dimensional structure of charybdotoxin, a high-affinity peptide blocker of several potassium ion channels, was determined by two-dimensional nuclear magnetic resonance (2-D NMR) spectroscopy. Unambiguous NMR assignments of backbone and side chain hydrogens were made for all 37 amino acids. The structure was determined by distance geometry and refined by nuclear Overhauser and exchange spectroscopy back calculation. The peptide is built on a foundation of three antiparallel beta strands to which other parts of the sequence are attached by three disulfide bridges. The overall shape is roughly ellipsoidal, with axes of approximately 2.5 and 1.5 nanometers. Nine of the ten charged groups are located on one side of the ellipsoid, with seven of the eight positive residues lying in a stripe 2.5 nanometers in length. The other side displays three hydrophobic residues projecting prominently into aqueous solution. The structure rationalizes several mechanistic features of charybdotoxin block of the high-conductance Ca2(+)-activated K+ channel.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Massefski, W Jr -- Redfield, A G -- Hare, D R -- Miller, C -- GM-20168/GM/NIGMS NIH HHS/ -- GM-31768/GM/NIGMS NIH HHS/ -- RR0031/RR/NCRR NIH HHS/ -- New York, N.Y. -- Science. 1990 Aug 3;249(4968):521-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Graduate Department of Biochemistry, Brandeis University, Waltham, MA 02254.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1696395" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Charybdotoxin ; Disulfides/analysis ; Magnetic Resonance Spectroscopy/methods ; Models, Molecular ; Molecular Sequence Data ; Potassium Channels/drug effects ; Protein Conformation ; *Scorpion Venoms/pharmacology
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  • 24
    Publication Date: 1990-12-21
    Description: Human growth hormone (hGH) elicits a diverse set of biological activities including lactation that derives from binding to the prolactin (PRL) receptor. The binding affinity of hGH for the extracellular binding domain of the hPRL receptor (hPRLbp) was increased about 8000-fold by addition of 50 micromolar ZnCl2. Zinc was not required for binding of hGH to the hGH binding protein (hGHbp) or for binding of hPRL to the hPRLbp. Other divalent metal ions (Ca2+, Mg2+, Cu2+, Mn2+, and Co2+) at physiological concentrations did not support such strong binding. Scatchard analysis indicated a stoichiometry of one Zn2+ per hGH.hPRLbp complex. Mutational analysis showed that a cluster of three residues (His18, His21, and Glu174) in hGH and His188 from the hPRLbp (conserved in all PRL receptors but not GH receptors) are probable Zn2+ ligands. This polypeptide hormone.receptor "zinc sandwich" provides a molecular mechanism to explain why nonprimate GHs are not lactogenic and offers a molecular link between zinc deficiency and its association with altered functions of hGH.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cunningham, B C -- Bass, S -- Fuh, G -- Wells, J A -- New York, N.Y. -- Science. 1990 Dec 21;250(4988):1709-12.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Protein Engineering, Genentech, Inc., South San Francisco, CA 94080.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2270485" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Base Sequence ; Binding Sites ; Chlorides/*pharmacology ; Growth Hormone/*metabolism ; Humans ; Kinetics ; Models, Molecular ; Molecular Sequence Data ; Mutagenesis, Site-Directed ; Oligonucleotide Probes ; Plasmids ; Protein Conformation ; Receptors, Prolactin/drug effects/genetics/*metabolism ; Restriction Mapping ; Zinc/metabolism/*pharmacology ; *Zinc Compounds
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  • 25
    Publication Date: 1990-11-23
    Description: Detailed kinetic investigations of a catalytic antibody that promotes the hydrolyses of an anilide and phenyl ester show that this catalyst uses a multistep kinetic sequence resembling that found in serine proteases to hydrolyze its substrates, although antibody was elicited to a single transition-state analog. Like the serine proteases the antibody catalyzes the hydrolysis reactions through a putative covalent intermediate, but unlike the enzymes it may use hydroxide ion to cleave the intermediates. Nevertheless, the antibody is a potent catalyst with turnover at higher pH values rivaling that of chymotrypsin. This analysis also reveals that turnover by the antibody is ultimately limited by product desorption, suggesting that improvements in catalytic efficiency may be achieved by judicious changes in the structure of the substrate, so that it is not superimposable on that of the eliciting hapten.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Benkovic, S J -- Adams, J A -- Borders, C L Jr -- Janda, K D -- Lerner, R A -- GM4385801/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Nov 23;250(4984):1135-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Pennsylvania State University, Department of Chemistry, University Park 16802.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2251500" target="_blank"〉PubMed〈/a〉
    Keywords: Acylation ; Aniline Compounds/metabolism ; Antibodies/*metabolism ; Catalysis ; Enzymes/*metabolism ; Hydrogen-Ion Concentration ; Hydrolysis ; Kinetics ; Nitrophenols/metabolism ; Spectrometry, Fluorescence ; Thermodynamics
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  • 26
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-05-11
    Description: Regulated expression of bacterial genes allows a pathogen to adapt to new environmental conditions within the host. The synthesis of over 30 Salmonella proteins is selectively induced during infection of macrophages. Two proteins induced by Salmonella are the heat shock proteins GroEL and DnaK. Two avirulent, macrophage-sensitive mutants of Salmonella synthesize GroEL and DnaK but fail to synthesize different subsets of proteins normally induced within the macrophage. Enhanced expression of selected Salmonella proteins contributes to bacterial survival within macrophages and may also contribute to the apparent immunodominance of heat shock proteins.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Buchmeier, N A -- Heffron, F -- New York, N.Y. -- Science. 1990 May 11;248(4956):730-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, Research Institute of Scripps Clinic, La Jolla, CA 92037.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1970672" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Bacterial Proteins/*biosynthesis/genetics/isolation & purification ; Cell Line ; Chaperonin 60 ; Electrophoresis, Gel, Two-Dimensional ; Electrophoresis, Polyacrylamide Gel ; *Escherichia coli Proteins ; *HSP70 Heat-Shock Proteins ; Heat-Shock Proteins/*biosynthesis/genetics/isolation & purification ; Kinetics ; Macrophages/*microbiology ; Molecular Weight ; Salmonella/*physiology
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  • 27
    Publication Date: 1990-07-20
    Description: Infection by human immunodeficiency virus type-1 (HIV-1) is initiated when its envelope protein, gp120, binds to its receptor, the cell surface glycoprotein CD4. Small molecules, termed N-carbomethoxycarbonyl-prolyl-phenylalanyl benzyl esters (CPFs), blocked this binding. CPFs interacted with gp120 and did not interfere with the binding of CD4 to class II major histocompatibility complex molecules. One CPF isomer, CPF(DD), preserved CD4-dependent T cell function while inhibiting HIV-1 infection of H9 tumor cells and human T cells. Although the production of viral proteins in infected T cells is unaltered by CPF(DD), this compound prevents the spread of infection in an in vitro model system.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Finberg, R W -- Diamond, D C -- Mitchell, D B -- Rosenstein, Y -- Soman, G -- Norman, T C -- Schreiber, S L -- Burakoff, S J -- New York, N.Y. -- Science. 1990 Jul 20;249(4966):287-91.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Dana-Farber Cancer Institute, Department of Medicine, Harvard Medical School, Boston, MA 02115.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2115689" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antigens, CD4/*immunology ; Antiviral Agents/*pharmacology ; Benzyl Compounds/pharmacology ; Cell Line ; Genes, MHC Class II ; HIV Envelope Protein gp120/*immunology ; HIV-1/drug effects/immunology/*physiology ; Humans ; Kinetics ; T-Lymphocytes/immunology
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  • 28
    Publication Date: 1990-07-20
    Description: Epidermal growth factor (EGF) treatment of A-431 epidermoid carcinoma cells elicited a redistribution of phospholipase C-gamma 1 (PLC-gamma 1) from a predominantly cytosolic localization to membrane fractions. The temporal coincidence of this redistribution with EGF stimulation of inositol phosphate formation and EGF increased phosphorylation of PLC-gamma 1 suggests that the membrane association of PLC-gamma 1 is a significant event in second messenger transduction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Todderud, G -- Wahl, M I -- Rhee, S G -- Carpenter, G -- CA24071/CA/NCI NIH HHS/ -- GM07347/GM/NIGMS NIH HHS/ -- T32 AM07491/AM/NIADDK NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1990 Jul 20;249(4966):296-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2374928" target="_blank"〉PubMed〈/a〉
    Keywords: Carcinoma, Squamous Cell ; Cell Line ; Cell Membrane/drug effects/enzymology ; Cytosol/enzymology ; Epidermal Growth Factor/*pharmacology ; Humans ; Isoenzymes/*metabolism ; Kinetics ; Phosphopeptides/isolation & purification ; Protein Binding ; Trypsin ; Type C Phospholipases/*metabolism
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  • 29
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-08-31
    Description: The sodium- and potassium-dependent adenosine triphosphatase (Na+,K(+)-ATPase) maintains the transmembrane Na+ gradient to which is coupled all active cellular transport systems. The R and S alleles of the gene encoding the Na+,K(+)-ATPase alpha 1 subunit isoform were identified in Dahl salt-resistant (DR) and Dahl salt-sensitive (DS) rats, respectively. Characterization of the S allele-specific Na+,K(+)-ATPase alpha 1 complementary DNA identified a leucine substitution of glutamine at position 276. This mutation alters the hydropathy profile of a region in proximity to T3(Na), the trypsin-sensitive site that is only detected in the presence of Na+. This mutation causes a decrease in the rubidium-86 influx of S allele-specific sodium pumps, thus marking a domain in the Na+,K(+)-ATPase alpha subunit important for K+ transport, and supporting the hypothesis of a putative role of these pumps in hypertension.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Herrera, V L -- Ruiz-Opazo, N -- HL 01967/HL/NHLBI NIH HHS/ -- HL 18318/HL/NHLBI NIH HHS/ -- HL 39267/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1990 Aug 31;249(4972):1023-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Section of Molecular Genetics, Whitaker Cardiovascular Institute, Boston University School of Medicine, MA 02118.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1975705" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Cell Membrane/enzymology ; Kidney/enzymology ; Kinetics ; Molecular Sequence Data ; *Mutation ; Polymorphism, Restriction Fragment Length ; Protein Conformation ; Rats ; Rats, Inbred Strains ; Rubidium/*metabolism ; Rubidium Radioisotopes ; Sodium-Potassium-Exchanging ATPase/*genetics/metabolism
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  • 30
    Publication Date: 1990-10-05
    Description: Rhodopsin is a member of a family of receptors that contain seven transmembrane helices and are coupled to G proteins. The nature of the interactions between rhodopsin mutants and the G protein, transduction (Gt), was investigated by flash photolysis in order to monitor directly Gt binding and dissociation. Three mutant opsins with alterations in their cytoplasmic loops bound 11-cis-retinal to yield pigments with native rhodopsin absorption spectra, but they failed to stimulate the guanosine triphosphatase activity of Gt. The opsin mutations included reversal of a charged pair conserved in all G protein-coupled receptors at the cytoplasmic border of the third transmembrane helix (mutant CD1), replacement of 13 amino acids in the second cytoplasmic loop (mutant CD2), and deletion of 13 amino acids from the third cytoplasmic loop (mutant EF1). Whereas mutant CD1 failed to bind Gt, mutants CD2 and EF1 showed normal Gt binding but failed to release Gt in the presence of guanosine triphosphate. Therefore, it appears that at least the second and third cytoplasmic loops of rhodopsin are required for activation of bound Gt.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Franke, R R -- Konig, B -- Sakmar, T P -- Khorana, H G -- Hofmann, K P -- New York, N.Y. -- Science. 1990 Oct 5;250(4977):123-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2218504" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Cell Line ; Cell Membrane/metabolism ; Chromosome Deletion ; Micelles ; Models, Molecular ; Molecular Sequence Data ; *Mutation ; Photolysis ; Protein Binding ; Protein Conformation ; Rhodopsin/genetics/*metabolism ; Transducin/*metabolism ; Transfection
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  • 31
    Publication Date: 1990-09-28
    Description: The proliferative potential of human diploid endothelial cells is finite, and cellular senescence in vitro is accompanied by the failure of the endothelial cell to respond to exogenous growth factors. Senescent human endothelial cells were shown to contain high amounts of the transcript for the cytokine interleukin-1 alpha (IL-1 alpha), a potent inhibitor of endothelial cell proliferation in vitro. In contrast, transformed human endothelial cells did not contain detectable IL-1 alpha messenger RNA. Treatment of human endothelial cell populations with an antisense oligodeoxynucleotide to the human IL-1 alpha transcript prevented cell senescence and extended the proliferative life-span of the cells in vitro. Removal of the IL-1 alpha antisense oligomer resulted in the generation of the senescent phenotype and loss of proliferative potential. These data suggest that human endothelial cell senescence in vitro is a dynamic process regulated by the potential intracellular activity of IL-1 alpha.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Maier, J A -- Voulalas, P -- Roeder, D -- Maciag, T -- AG07450/AG/NIA NIH HHS/ -- HL32348/HL/NHLBI NIH HHS/ -- HL35627/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1990 Sep 28;249(4976):1570-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Molecular Biology, Jerome H. Holland, Laboratory for the Biomedical Sciences, American Red Cross, Rockville, MD 20855.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2218499" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Cell Division ; Cell Survival ; Cells, Cultured ; Endothelium, Vascular/*cytology/physiology ; Humans ; Interleukin-1/*genetics ; Kinetics ; Molecular Sequence Data ; Oligonucleotide Probes ; RNA, Antisense/*genetics
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  • 32
    Publication Date: 1990-09-21
    Description: Calmodulin is a calcium-binding protein that participates in the transduction of calcium signals. The electric phenotypes of calmodulin mutants of Paramecium have suggested that the protein may regulate some calcium-dependent ion channels. Calcium-dependent sodium single channels in excised patches of the plasma membrane from Paramecium were identified, and their activity was shown to decrease after brief exposure to submicromolar concentrations of calcium. Channel activity was restored to these inactivated patches by adding calmodulin that was isolated from Paramecium to the cytoplasmic surface. This restoration of channel activity did not require adenosine triphosphate and therefore, probably resulted from direct binding of calmodulin, either to the sodium channel itself or to a channel regulator that was associated with the patch membrane.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Saimi, Y -- Ling, K Y -- GM22714/GM/NIGMS NIH HHS/ -- GM36386/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Sep 21;249(4975):1441-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Molecular Biology, University of Wisconsin-Madison 53706.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2169650" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Calcium/*pharmacology ; Calmodulin/genetics/*pharmacology/physiology ; Cell Membrane/physiology ; Kinetics ; Models, Biological ; Paramecium/*physiology ; Sodium Channels/drug effects/*physiology
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  • 33
    Publication Date: 1990-12-14
    Description: A chemical description of the action of phospholipase A2 (PLA2) can now be inferred with confidence from three high-resolution x-ray crystal structures. The first is the structure of the PLA2 from the venom of the Chinese cobra (Naja naja atra) in a complex with a phosphonate transition-state analogue. This enzyme is typical of a large, well-studied homologous family of PLA2S. The second is a similar complex with the evolutionarily distant bee-venom PLA2. The third structure is the uninhibited PLA2 from Chinese cobra venom. Despite the different molecular architectures of the cobra and bee-venom PLA2s, the transition-state analogue interacts in a nearly identical way with the catalytic machinery of both enzymes. The disposition of the fatty-acid side chains suggests a common access route of the substrate from its position in the lipid aggregate to its productive interaction with the active site. Comparison of the cobra-venom complex with the uninhibited enzyme indicates that optimal binding and catalysis at the lipid-water interface is due to facilitated substrate diffusion from the interfacial binding surface to the catalytic site rather than an allosteric change in the enzyme's structure. However, a second bound calcium ion changes its position upon the binding of the transition-state analogue, suggesting a mechanism for augmenting the critical electrophile.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3443688/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3443688/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Scott, D L -- White, S P -- Otwinowski, Z -- Yuan, W -- Gelb, M H -- Sigler, P B -- GM22324/GM/NIGMS NIH HHS/ -- HL36235/HL/NHLBI NIH HHS/ -- R01 HL036235/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1990 Dec 14;250(4987):1541-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2274785" target="_blank"〉PubMed〈/a〉
    Keywords: Bee Venoms/analysis ; Binding Sites ; Calcium/metabolism ; Catalysis ; Chemistry, Physical ; Cobra Venoms/analysis ; Models, Molecular ; Molecular Structure ; Organophosphonates/metabolism ; Phospholipases A/chemistry/*metabolism ; Phospholipases A2 ; Phospholipids/metabolism ; Physicochemical Phenomena ; Protein Conformation ; X-Ray Diffraction
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  • 34
    Publication Date: 1990-03-16
    Description: An amino acid sequence encodes a message that determines the shape and function of a protein. This message is highly degenerate in that many different sequences can code for proteins with essentially the same structure and activity. Comparison of different sequences with similar messages can reveal key features of the code and improve understanding of how a protein folds and how it performs its function.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bowie, J U -- Reidhaar-Olson, J F -- Lim, W A -- Sauer, R T -- AI-15706/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1990 Mar 16;247(4948):1306-10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2315699" target="_blank"〉PubMed〈/a〉
    Keywords: *Amino Acid Sequence ; Computer Graphics ; *DNA-Binding Proteins ; Models, Molecular ; Molecular Sequence Data ; Protein Conformation ; Proteins/*physiology/ultrastructure ; Repressor Proteins ; Structure-Activity Relationship ; Surface Properties ; Viral Proteins ; Viral Regulatory and Accessory Proteins
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  • 35
    Publication Date: 1990-02-02
    Description: A rapid increase in the RNA levels of the proto-oncogenes c-fos, c-jun, and c-myc was detected after human cytomegalovirus infection. Neither inactivation of viral infectivity with ultraviolet irradiation (with or without psoralen), nor inhibition of translation with cycloheximide or anisomycin adversely affected the enhanced expression of proto-oncogenes, even though these treatments substantially reduced or eliminated the detection of immediate early viral antigens. The increase in the RNA levels of the proto-oncogenes was prevented in the presence of alpha-amanitin or actinomycin D. Thus, expression of these oncogenes appears to be induced by events occurring before the onset of viral protein synthesis, perhaps by the interaction of viral particles with the cell surface.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Boldogh, I -- AbuBakar, S -- Albrecht, T -- New York, N.Y. -- Science. 1990 Feb 2;247(4942):561-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology, University of Texas Medical Branch, Galveston 77550.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1689075" target="_blank"〉PubMed〈/a〉
    Keywords: Cell Line ; Cytomegalovirus/*genetics ; DNA-Binding Proteins/genetics ; *Gene Expression Regulation, Viral ; Humans ; Kinetics ; Lung ; Protein-Tyrosine Kinases/genetics ; Proto-Oncogene Proteins/genetics ; Proto-Oncogene Proteins c-fos ; Proto-Oncogene Proteins c-jun ; Proto-Oncogene Proteins c-myc ; *Proto-Oncogenes ; RNA/genetics/isolation & purification ; Transcription Factors/genetics ; Transcription, Genetic
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  • 36
    Publication Date: 1990-12-21
    Description: lambda Cro is a dimeric DNA binding protein. Random mutagenesis and a selection for Cro activity have been used to identify the contacts between Cro subunits that are crucial for maintenance of a stably folded structure. To obtain equivalent contacts in a monomeric system, a Cro variant was designed and constructed in which the antiparallel beta-ribbon that forms the dimer interface was replaced by a beta-hairpin. The engineered monomer has a folded structure similar to wild type, is significantly more stable than wild type, and exhibits novel half-operator binding activity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mossing, M C -- Sauer, R T -- AI-16982/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1990 Dec 21;250(4988):1712-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2148648" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Bacteriophage lambda/*genetics ; Circular Dichroism ; *DNA-Binding Proteins ; Escherichia coli/genetics ; *Genetic Variation ; Macromolecular Substances ; Models, Molecular ; Molecular Sequence Data ; Mutagenesis ; Protein Conformation ; Repressor Proteins/*genetics/metabolism ; Thermodynamics ; Transcription Factors/*genetics ; Viral Proteins ; Viral Regulatory and Accessory Proteins
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  • 37
    Publication Date: 1990-07-13
    Description: The three-dimensional structure of the DNA-binding domain (DBD) of the glucocorticoid receptor has been determined by nuclear magnetic resonance spectroscopy and distance geometry. The structure of a 71-residue protein fragment containing two "zinc finger" domains is based on a large set of proton-proton distances derived from nuclear Overhauser enhancement spectra, hydrogen bonds in previously identified secondary structure elements, and coordination of two zinc atoms by conserved cysteine residues. The DBD is found to consist of a globular body from which the finger regions extend. A model of the dimeric complex between the DBD and the glucocorticoid response element is proposed. The model is consistent with previous results indicating that specific amino acid residues of the DBD are involved in protein-DNA and protein-protein interactions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hard, T -- Kellenbach, E -- Boelens, R -- Maler, B A -- Dahlman, K -- Freedman, L P -- Carlstedt-Duke, J -- Yamamoto, K R -- Gustafsson, J A -- Kaptein, R -- New York, N.Y. -- Science. 1990 Jul 13;249(4965):157-60.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of Utrecht, The Netherlands.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2115209" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; DNA/*metabolism ; DNA-Binding Proteins/analysis/*metabolism ; Humans ; Magnetic Resonance Spectroscopy ; Metalloproteins/analysis ; Models, Molecular ; Molecular Sequence Data ; Peptide Fragments/analysis/metabolism ; Protein Conformation ; Rats ; Receptors, Glucocorticoid/*analysis/metabolism ; Regulatory Sequences, Nucleic Acid ; Zinc/analysis
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  • 38
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-02-16
    Description: Activin, a member of the transforming growth factor beta protein family, was originally isolated from gonadal fluids and stimulates the release of pituitary follicle-stimulating hormone (FSH). Activin has numerous functions in both normal and neoplastic cells. Various cells synthesize activin and have a specific binding site for this peptide. However, the molecular basis for its actions is unknown. A binding protein for activin was purified from rat ovary and was identical to follistatin, a specific inhibitor of FSH release. It is likely that the binding protein participates in the diverse regulatory actions of activin.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Nakamura, T -- Takio, K -- Eto, Y -- Shibai, H -- Titani, K -- Sugino, H -- New York, N.Y. -- Science. 1990 Feb 16;247(4944):836-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Frontier Research Program, Institute of Physical and Chemical Research (RIKEN), Saitama, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2106159" target="_blank"〉PubMed〈/a〉
    Keywords: Activins ; Animals ; *Carrier Proteins ; Cells, Cultured ; Female ; Follicle Stimulating Hormone/secretion ; Inhibins/isolation & purification/*metabolism/pharmacology ; Kinetics ; Molecular Weight ; Ovary/*metabolism ; Pituitary Gland/drug effects/secretion ; Protein Binding ; Rats
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  • 39
    Publication Date: 1990-05-04
    Description: Although bacteriophage T4 late promoters are selectively recognized by Escherichia coli RNA polymerase bearing a single protein encoded by T4 gene 55 (gp55), efficient transcription at these promoters requires enhancement by the three T4 DNA polymerase accessory proteins, bound to distal "mobile enhancer" sites. Two principles are shown to govern this transcriptional enhancement: (i) Promoter recognition and communication between the enhancer and the promoter require separate phage-coded proteins. Only RNA polymerase that has the T4 gene 33 protein (gp33) bound to it is subject to enhancement by the three DNA replication proteins. (ii) Transcriptional enhancement in this prokaryotic system is promoter-specific. Promoter specificity is generated by a direct competition of phage T4 gp33 and gp55 with the E. coli promoter recognition protein, sigma 70, for binding to the E. coli RNA polymerase core. Thus, polymerase that contains sigma 70 is competent to transcribe T4 early and middle genes, but lacks the ability to be enhanced by the DNA replication proteins, while polymerase that contains gp55 and gp33 is capable of enhancement via gp33, but its activity is restricted to T4 late promoters by gp55.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Herendeen, D R -- Williams, K P -- Kassavetis, G A -- Geiduschek, E P -- New York, N.Y. -- Science. 1990 May 4;248(4955):573-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, University of California, San Diego, La Jolla 92093.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2185541" target="_blank"〉PubMed〈/a〉
    Keywords: Carrier Proteins/isolation & purification/*physiology ; DNA-Directed RNA Polymerases/*metabolism ; *Enhancer Elements, Genetic ; Escherichia coli/enzymology/*genetics ; Kinetics ; Models, Genetic ; *Promoter Regions, Genetic ; T-Phages/*genetics ; *Transcription Factors ; Viral Proteins/isolation & purification/*metabolism
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  • 40
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-08-17
    Description: The major small nuclear ribonucleoprotein particles (snRNPs) U1, U2, U4 + U6, and U5 have to be transported from the cytoplasm, where they are synthesized, to the nucleus, where they splice pre-messenger RNAs. Since the free core snRNP proteins in the cytoplasm do not enter the nucleus on their own, the nuclear location signal must either reside on the snRNA or be created as a result of snRNA-protein interaction. Here the involvement by the 5'-terminal cap of snRNA molecules in the nucleo-cytoplasmic transport of UsnRNPs has been studied by microinjection of synthetic U1 RNA molecules into frog oocytes; the U1 RNA bore either the normal cap (m3G) or a chemical derivative. Antibodies in the cytoplasm against the m3G cap inhibited the nuclear uptake of U1 snRNP. U1 RNA that was uncapped or contained an unnatural ApppG cap did not enter the nucleus, even though it carried a normal complement of protein molecules. When the ribose ring of the m3G cap was oxidized with periodate, nuclear transport of U1 snRNPs was severely inhibited. Finally, microinjection of m3G cap alone (but not m7G cap) into oocytes severely inhibited the transport of U1 snRNPs to the nucleus. These data suggest that one step in the nuclear uptake of U1 snRNPs involves the m3G cap structure.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Fischer, U -- Luhrmann, R -- New York, N.Y. -- Science. 1990 Aug 17;249(4970):786-90.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institut fur Molekularbiologie und Tumorforschung, Phillipps-Universitat Marburg, Federal Republic of Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2143847" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biological Transport ; Cell Nucleus/*metabolism ; Cytoplasm/metabolism ; Female ; Guanosine/*analogs & derivatives/physiology ; Kinetics ; Mutation ; Oocytes/*ultrastructure ; RNA Caps/*physiology ; Ribonucleoproteins/genetics/*metabolism ; Ribonucleoproteins, Small Nuclear ; Signal Transduction/*physiology ; Xenopus laevis
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  • 41
    Publication Date: 1990-02-16
    Description: Confocal laser-scanned microscopy and long-wavelength calcium (Ca2+) indicators were combined to monitor both sustained and rapidly dissipating Ca2+ gradients in voltage-clamped sympathetic neurons isolated from the bullfrog. After a brief activation of voltage-dependent Ca2+ channels, Ca2+ spreads inwardly, and reaches the center of these spherical cells in about 300 milliseconds. Although the Ca2+ redistribution in the bulk of the cytosol could be accounted for with a radial diffusion model, local nonlinearities, suggesting either nonuniform Ca2+ entry or spatial buffering, could be seen. After electrical stimulation, Ca2+ signals in the nucleus were consistently larger and decayed more slowly than those in the cytosol. A similar behavior was observed when release of intracellular Ca2+ was induced by caffeine, suggesting that in both cases large responses originate from Ca2+ release sites near or within the nucleus. These results are consistent with an amplification mechanism involving Ca2(+)-induced Ca2+ release, which could be relevant to activity-dependent, Ca2(+)-regulated nuclear events.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hernandez-Cruz, A -- Sala, F -- Adams, P R -- NS1857906/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1990 Feb 16;247(4944):858-62.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Neurobiology and Behavior, State University of New York, Stony Brook 11794.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2154851" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Caffeine/pharmacology ; Calcium/*metabolism ; Calcium Channels/*physiology ; Cytosol/metabolism ; Fluorescent Dyes ; Ganglia, Sympathetic/drug effects/physiology ; In Vitro Techniques ; Kinetics ; Membrane Potentials ; Microscopy, Fluorescence/methods ; Neurons/cytology/drug effects/*physiology ; Rana catesbeiana
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  • 42
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-01-12
    Description: Experiments are presented that confirm earlier predictions that the mode of supply of reactants to a nonlinear (bio)chemical reaction determines or controls concentrations at steady states far from equilibrium. The oxidation of nicotinamide adenine dinucleotide (NADH) catalyzed by the enzyme horseradish peroxidase with continuous input of oxygen was studied; NAD+ is continuously recycled to NADH through a glucose-6-phosphate dehydrogenase system. A comparison of steady-state concentrations is made with an oscillatory oxygen input and a constant input at the same average oxygen input for both modes. By varying the frequency and amplitude of the perturbation (O2 influx), the following may be changed: the average concentration of NADH; the Gibbs free energy difference delta G of the reactants and products at steady state; the average rate of the reaction; the phase relation between the oscillatory rate and delta G; and the dissipation. These results confirm the possibility of an "alternating current chemistry," of control and optimization of thermodynamic efficiency and dissipation by means of external variation of constraints in classes of nonlinear reactions and biological pumps, and of improvements of the yield in such reactions (heterogeneous catalysis, for example).〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lazar, J G -- Ross, J -- New York, N.Y. -- Science. 1990 Jan 12;247(4939):189-92.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Stanford University, CA 94305.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2294601" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/metabolism ; Chemical Phenomena ; Chemistry ; Glucosephosphate Dehydrogenase/*metabolism ; Horseradish Peroxidase/*metabolism ; Kinetics ; NAD/*metabolism ; Oxidation-Reduction ; Oxygen/metabolism ; Peroxidases/*metabolism ; Thermodynamics
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  • 43
    Publication Date: 1990-05-11
    Description: The endosomal compartment of polarized epithelial cells is a major crossroads for membrane traffic. Proteins entering this compartment from the cell surface are sorted for transport to one of several destinations: recycling to the original cell surface, targeting to lysosomes for degradation, or transcytosis to the opposite surface. The polymeric immunoglobulin receptor (pIgR), which is normally transcytosed from the basolateral to the apical surface, was used as a model to dissect the signals that mediate this sorting event. When exogenous receptor was expressed in Madin-Darby Canine Kidney (MDCK) cells, it was shown that phosphorylation of pIgR at the serine residue at position 664 is required for efficient transcytosis. Replacement of this serine with alanine generated a receptor that is transcytosed only slowly, and appears to be recycled. Conversely, substitution with aspartic acid (which mimics the negative charge of the phosphate group) results in rapid transcytosis. It was concluded that phosphorylation is the signal that directs the pIgR from the endosome into the transcytotic pathway.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Casanova, J E -- Breitfeld, P P -- Ross, S A -- Mostov, K E -- R01-AI-25144/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1990 May 11;248(4956):742-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Anatomy, University of California, San Francisco 94143.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2110383" target="_blank"〉PubMed〈/a〉
    Keywords: Alanine ; Animals ; Aspartic Acid ; Cell Line ; Cell Membrane/immunology/metabolism ; Endocytosis ; Immunoglobulin A/metabolism ; Kinetics ; Ligands ; Membrane Glycoproteins/metabolism ; Molecular Weight ; Mutation ; Phosphorylation ; Rats ; Receptors, Immunologic ; Secretory Component/genetics/*metabolism ; Serine
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  • 44
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-10-26
    Description: The potassium channels encoded by the Drosophila Shaker gene activate and inactivate rapidly when the membrane potential becomes more positive. Site-directed mutagenesis and single-channel patch-clamp recording were used to explore the molecular transitions that underlie inactivation in Shaker potassium channels expressed in Xenopus oocytes. A region near the amino terminus with an important role in inactivation has now been identified. The results suggest a model where this region forms a cytoplasmic domain that interacts with the open channel to cause inactivation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hoshi, T -- Zagotta, W N -- Aldrich, R W -- NS07158/NS/NINDS NIH HHS/ -- NS23294/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1990 Oct 26;250(4980):533-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular and Cellular Physiology, Stanford University, School of Medicine, CA 94305.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2122519" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; DNA/genetics ; Drosophila melanogaster/*genetics ; Electric Conductivity ; Ion Channel Gating/drug effects/*physiology ; Kinetics ; Membrane Potentials/physiology ; Molecular Sequence Data ; Mutagenesis ; Mutagenesis, Site-Directed ; Oocytes/metabolism ; Potassium Channels/genetics/*physiology ; RNA Splicing ; Structure-Activity Relationship ; Trypsin/pharmacology ; Xenopus
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  • 45
    Publication Date: 1990-04-13
    Description: Biosynthetic studies of the prion protein (PrP) have shown that two forms of different topology can be generated from the same pool of nascent chains in cell-free translation systems supplemented with microsomal membranes. A transmembrane form is the predominant product generated in wheat germ (WG) extracts, whereas a completely translocated (secretory) form is the major product synthesized in rabbit reticulocyte lysates (RRL). An unusual topogenic sequence within PrP is now shown to direct this system-dependent difference. The actions of this topogenic sequence were independent of on-going translation and could be conferred to heterologous proteins by the engineering of a discrete set of codons. System-dependent topology conferred by addition of RRL to WG translation products suggests that this sequence interacts with one or more cytosolic factors.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lopez, C D -- Yost, C S -- Prusiner, S B -- Myers, R M -- Lingappa, V R -- AG02132/AG/NIA NIH HHS/ -- NS14069/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1990 Apr 13;248(4952):226-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology, University of California, San Francisco 94143.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1970195" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Codon ; Cricetinae ; DNA, Viral/genetics ; Kinetics ; Mesocricetus ; Peptide Mapping ; Plasmids ; PrPSc Proteins ; Prions/*genetics ; Protein Biosynthesis ; Protein Processing, Post-Translational ; Restriction Mapping ; Transcription, Genetic ; Viral Proteins/biosynthesis/*genetics
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  • 46
    Publication Date: 1990-10-26
    Description: The role of defective glucose transport in the pathogenesis of noninsulin-dependent diabetes (NIDDM) was examined in Zucker diabetic fatty rats, a model of NIDDM. As in human NIDDM, insulin secretion was unresponsive to 20 mM glucose. Uptake of 3-O-methylglucose by islet cells was less than 19% of controls. The beta cell glucose transporter (GLUT-2) immunoreactivity and amount of GLUT-2 messenger RNA were profoundly reduced. Whenever fewer than 60% of beta cells were GLUT-2-positive, the response to glucose was absent and hyperglycemia exceeded 11 mM plasma glucose. We conclude that in NIDDM underexpression of GLUT-2 messenger RNA lowers high Km glucose transport in beta cells, and thereby impairs glucose-stimulated insulin secretion and prevents correction of hyperglycemia.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Johnson, J H -- Ogawa, A -- Chen, L -- Orci, L -- Newgard, C B -- Alam, T -- Unger, R H -- DK02700-30/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1990 Oct 26;250(4980):546-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Diabetes Research, University of Texas, Dallas 75235.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2237405" target="_blank"〉PubMed〈/a〉
    Keywords: 3-O-Methylglucose ; Animals ; Biological Transport ; Diabetes Mellitus/metabolism ; Diabetes Mellitus, Experimental/*metabolism ; Diabetes Mellitus, Type 2/*metabolism ; Female ; *Gene Expression ; Glucose/pharmacology ; Immunoblotting ; Insulin/secretion ; Islets of Langerhans/drug effects/*metabolism ; Kinetics ; Male ; Methylglucosides/metabolism ; Monosaccharide Transport Proteins/*genetics/metabolism ; Obesity ; RNA, Messenger/metabolism ; Rats ; Rats, Inbred Strains ; Rats, Zucker
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  • 47
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-12-21
    Description: A major mechanism for generating tolerance in developing T cells is the intrathymic clonal deletion of T cells that have receptors for those self antigens that are presented on hematopoietic cells. The mechanisms of tolerance induction to antigens not expressed in the thymus remain unclear. Tolerance to self antigens can be generated extrathymically through the induction of clonal nonresponsiveness in T cells with self-reactive receptors. A second mechanism of extrathymic tolerance was identified: clonal elimination of mature T cells with self-reactive receptors that had previously displayed functional reactivity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jones, L A -- Chin, L T -- Longo, D L -- Kruisbeek, A M -- New York, N.Y. -- Science. 1990 Dec 21;250(4988):1726-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Biological Response Modifiers Program, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2125368" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antibodies, Monoclonal/immunology ; Antigens, CD4/analysis ; Antigens, CD8 ; Antigens, Differentiation, T-Lymphocyte/analysis ; Clone Cells ; *Immune Tolerance ; Kinetics ; *Lymphocyte Depletion ; Mice ; Mice, Inbred DBA ; Mice, Inbred Strains ; Spleen/immunology ; T-Lymphocytes/cytology/*immunology ; Thymus Gland/immunology
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  • 48
    Publication Date: 1990-07-20
    Description: Angiotensin II (AII) stimulates rapid increases in the concentration of cytosolic calcium in follicular oocytes from Xenopus laevis. This calcium response was not present in denuded oocytes, indicating that it is mediated by AII receptors on the adherent follicular cells. The endogenous AII receptors differed in their binding properties from mammalian AII receptors expressed on the oocyte surface after injection of rat adrenal messenger RNA. Also, the calcium responses to activation of the amphibian AII receptor, but not the expressed mammalian AII receptor, were blocked reversibly by octanol and intracellular acidification, treatments that inhibit cell coupling through gap junctions. In addition, AII increased the rate of progesterone-induced maturation. Thus, an AII-induced calcium-mobilizing signal is transferred from follicle cells to the oocyte through gap junctions and may play a physiological role in oocyte maturation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sandberg, K -- Bor, M -- Ji, H -- Markwick, A -- Millan, M A -- Catt, K J -- New York, N.Y. -- Science. 1990 Jul 20;249(4966):298-301.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Endocrinology and Reproduction Research Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2374929" target="_blank"〉PubMed〈/a〉
    Keywords: Aequorin ; Angiotensin II/*analogs & derivatives/metabolism/*pharmacology ; Animals ; Calcium/*metabolism ; Cytosol/drug effects/metabolism ; Female ; Intercellular Junctions/drug effects/*physiology ; Kinetics ; Luminescence ; Oocytes/drug effects/*physiology ; Progesterone/pharmacology ; Receptors, Angiotensin/metabolism ; *Signal Transduction/drug effects ; Structure-Activity Relationship ; Xenopus laevis
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  • 49
    Publication Date: 1990-08-17
    Description: The interaction of a protein antigen, horse cytochrome c (cyt c), with a monoclonal antibody has been studied by hydrogen-deuterium (H-D) exchange labeling and two-dimensional nuclear magnetic resonance (2D NMR) methods. The H-exchange rate of residues in three discontiguous regions of the cyt c polypeptide backbone was slowed by factors up to 340-fold in the antibody-antigen complex compared with free cyt c. The protected residues, 36 to 38, 59, 60, 64 to 67, 100, and 101, and their hydrogen-bond acceptors, are brought together in the three-dimensional structure to form a contiguous, largely exposed protein surface with an area of about 750 square angstroms. The interaction site determined in this way is consistent with prior epitope mapping studies and includes several residues that were not previously identified. The hydrogen exchange labeling approach can be used to map binding sites on small proteins in antibody-antigen complexes and may be applicable to protein-protein and protein-ligand interactions in general.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3432411/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3432411/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Paterson, Y -- Englander, S W -- Roder, H -- GM 31847/GM/NIGMS NIH HHS/ -- GM 35926/GM/NIGMS NIH HHS/ -- R01 GM031847/GM/NIGMS NIH HHS/ -- S07-RR-05415-28/RR/NCRR NIH HHS/ -- New York, N.Y. -- Science. 1990 Aug 17;249(4970):755-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology, University of Pennsylvania, Philadelphia 19104.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1697101" target="_blank"〉PubMed〈/a〉
    Keywords: Antibodies, Monoclonal/immunology/metabolism ; Antigen-Antibody Complex ; *Binding Sites, Antibody ; Chemical Phenomena ; Chemistry ; Cytochrome c Group/*immunology ; Deuterium ; Epitopes/immunology ; Hydrogen/*metabolism ; Hydrogen Bonding ; Kinetics ; *Magnetic Resonance Spectroscopy ; Molecular Structure ; Protein Conformation
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  • 50
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-12-21
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Barinaga, M -- New York, N.Y. -- Science. 1990 Dec 21;250(4988):1657-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2270477" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antigens, Viral/immunology ; Histocompatibility Antigens Class I/genetics/*immunology ; Humans ; *Immunity, Cellular ; *Major Histocompatibility Complex ; Models, Molecular ; Protein Conformation
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  • 51
    Publication Date: 1990-05-18
    Description: In Saccharomyces cerevisiae, the product of the CDC25 gene controls the RAS-mediated production of adenosine 3',5'-monophosphate (cAMP). In vivo the carboxyl-terminal third of the CDC25 gene product is sufficient for the activation of adenylate cyclase. The 3'-terminal part of SCD25, a gene of S. cerevisiae structurally related to CDC25, can suppress the requirement for CDC25. Partially purified preparations of the carboxy-terminal domain of the SCD25 gene product enhanced the exchange rate of guanosine diphosphate (GDP) to guanosine triphosphate (GTP) of pure RAS2 protein by stimulating the release of GDP. This protein fragment had a similar effect on the human c-H-ras-encoded p21 protein. Thus, the SCD25 carboxyl-terminal domain can enhance the regeneration of the active form of RAS proteins.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Crechet, J B -- Poullet, P -- Mistou, M Y -- Parmeggiani, A -- Camonis, J -- Boy-Marcotte, E -- Damak, F -- Jacquet, M -- New York, N.Y. -- Science. 1990 May 18;248(4957):866-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratoire de Biochimie, URA 240 du CNRS, Ecole Polytechnique, Palaiseau, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2188363" target="_blank"〉PubMed〈/a〉
    Keywords: *Cell Cycle Proteins ; Escherichia coli/genetics ; Fungal Proteins/genetics/*metabolism/*pharmacology ; Genes, Fungal ; Guanine Nucleotides/*metabolism ; Guanosine Diphosphate/*metabolism ; Guanosine Triphosphate/*metabolism ; Humans ; Kinetics ; Peptide Fragments/*pharmacology ; Plasmids ; Proto-Oncogene Proteins/metabolism ; Proto-Oncogene Proteins p21(ras) ; Recombinant Fusion Proteins ; Saccharomyces cerevisiae/genetics ; *Saccharomyces cerevisiae Proteins ; Transfection ; *ras Proteins ; *ras-GRF1
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  • 52
    Publication Date: 1990-08-03
    Description: Four cloned cDNAs encoding 900-amino acid putative glutamate receptors with approximately 70 percent sequence identity were isolated from a rat brain cDNA library. In situ hybridization revealed differential expression patterns of the cognate mRNAs throughout the brain. Functional expression of the cDNAs in cultured mammalian cells generated receptors displaying alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-selective binding pharmacology (AMPA = quisqualate greater than glutamate greater than kainate) as well as cation channels gated by glutamate, AMPA, and kainate and blocked by 6,7-dinitroquinoxaline-2,3-dione (CNQX).〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Keinanen, K -- Wisden, W -- Sommer, B -- Werner, P -- Herb, A -- Verdoorn, T A -- Sakmann, B -- Seeburg, P H -- New York, N.Y. -- Science. 1990 Aug 3;249(4968):556-60.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Molecular Neuroendocrinology, University of Heidelberg, F.R.G.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2166337" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Base Sequence ; Brain/*metabolism/physiology ; Glutamates/metabolism/pharmacology ; Ibotenic Acid/analogs & derivatives/*pharmacology ; Kainic Acid/pharmacology ; Kinetics ; Molecular Sequence Data ; *Multigene Family ; Oligonucleotide Probes ; Organ Specificity ; Oxadiazoles/pharmacology ; Oxazoles/*pharmacology ; Quisqualic Acid ; RNA, Messenger/analysis/genetics ; Rats ; Receptors, Glutamate ; Receptors, Neurotransmitter/drug effects/*genetics/physiology ; Sequence Homology, Nucleic Acid ; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid
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  • 53
    Publication Date: 1990-09-07
    Description: A protein crystal structure is usually described by one single structure, which largely omits the dynamical behavior of the molecule. A molecular dynamics method with a time-averaged crystallographic restraint was used to overcome this limitation. This method yields an ensemble of structures in which all possible thermal motions are allowed, that is, in additional to isotropic distributions, anisotropic and anharmonic positional distributions occur as well. In the case of bovine pancreatic phospholipase A2, this description markedly improves agreement with the observed x-ray diffraction data compared to the results of the classical one-model structure description. Time-averaged crystallographically restrained molecular dynamics reveals large mobilities in the loops involved in lipid bilayer association.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gros, P -- van Gunsteren, W F -- Hol, W G -- New York, N.Y. -- Science. 1990 Sep 7;249(4973):1149-52.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉BIOSON Research Institute, University of Groningen, The Netherlands.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2396108" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cattle ; Crystallography ; Hot Temperature ; Models, Molecular ; Motion ; *Phospholipases ; *Phospholipases A ; Phospholipases A2 ; Protein Conformation ; X-Ray Diffraction
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  • 54
    Publication Date: 1990-07-20
    Description: The 70-residue carboxyl-terminal domain of the muscle contractile protein troponin-C contains two helix-loop-helix calcium (Ca)-binding sites that are related to each other by approximate twofold rotational symmetry. Hydrophobic residues from the helices and a short three residue beta sheet at the interface of the two sites act to stabilize the protein domain in the presence of Ca. A synthetic 34-residue peptide representing one of these sites (site III) has been synthesized and studied by H-1 nuclear magnetic resonance (NMR) spectroscopy. In solution this peptide undergoes a Ca-induced conformational change to form the helix-loop-helix Ca-binding motif. Two-dimensional nuclear Overhauser effect spectra have provided evidence for the formation of a beta sheet and interactions between several hydrophobic residues from opposing helices as found in troponin-C. It is proposed that a symmetric two-site dimer similar in tertiary structure to the carboxyl-terminal domain of troponin-C forms from the assembly of two site III peptides in the Ca-bound form.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shaw, G S -- Hodges, R S -- Sykes, B D -- New York, N.Y. -- Science. 1990 Jul 20;249(4966):280-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, University of Alberta, Edmonton, Canada.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2374927" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Binding Sites ; Calcium/*metabolism/pharmacology ; Hydrogen ; Magnetic Resonance Spectroscopy/methods ; Models, Molecular ; Molecular Sequence Data ; Peptides/chemical synthesis/*metabolism ; Protein Conformation ; Troponin/chemical synthesis/*metabolism ; Troponin C ; Turkeys
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  • 55
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-08-03
    Description: Yersinia is the genus of bacteria that is the causative agent in plague or the black death, and on several occasions this organism has killed a significant portion of the world's population. An essential virulence determinant of Yersinia was shown to be a protein tyrosine phosphatase. The recombinant 50-kilodalton Yersinia phosphatase had a specificity for removal of phosphate from Tyr-containing as opposed to Ser/Thr-containing phosphopeptides and proteins. Site-directed mutagenesis was used to show that the Yersinia phosphatase possesses an essential Cys residue required for catalysis. Amino acids surrounding an essential Cys residue are highly conserved, as are other amino acids in the Yersinia and mammalian protein tyrosine phosphatases, suggesting that they use a common catalytic mechanism.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Guan, K L -- Dixon, J E -- 18849/PHS HHS/ -- New York, N.Y. -- Science. 1990 Aug 3;249(4968):553-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, Purdue University, West Lafayette, IN 47907.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2166336" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Kinetics ; Molecular Sequence Data ; Phosphoprotein Phosphatases/*genetics/metabolism ; Protein Tyrosine Phosphatases ; Sequence Homology, Nucleic Acid ; Virulence/genetics ; Yersinia/enzymology/genetics/*pathogenicity
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  • 56
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-11-30
    Description: Deep inflation of the lung stimulates surfactant secretion by unknown mechanisms. The hypothesis that mechanical distension directly stimulates type II cells to secrete surfactant was tested by stretching type II cells cultured on silastic membranes. The intracellular Ca2+ concentration was measured in single cells, before and after stretching. A single stretch of alveolar type II cells caused a transient (less than 60 seconds) increase in cytosolic Ca2+ followed by a sustained (15 to 30 minutes) stimulation of surfactant secretion. Both Ca2+ mobilization and exocytosis exhibited dose-dependence to the magnitude of the stretch-stimulus. Thus, mechanical factors can trigger complex cellular events in nonneuron, nonmuscle cells and may be involved in regulating normal lung functions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wirtz, H R -- Dobbs, L G -- HL-24075/HL/NHLBI NIH HHS/ -- HL-34356/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1990 Nov 30;250(4985):1266-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Cardiovascular Research Institute, University of California, San Francisco 94143-0130.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2173861" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biomechanical Phenomena ; Calcium/*metabolism ; Cells, Cultured ; Cyclic AMP/metabolism ; Epithelium/physiology ; *Exocytosis ; Kinetics ; Phosphatidylcholines/secretion ; Proteolipids/pharmacology ; Pulmonary Alveoli/*physiology ; Pulmonary Surfactant-Associated Proteins ; Pulmonary Surfactants/pharmacology/secretion ; Rats ; Surface Properties ; Tetradecanoylphorbol Acetate/pharmacology
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  • 57
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-08-24
    Description: During fruiting body morphogenesis of Myxococcus xanthus, cell movement is required for transmission of C-factor, a short range intercellular signaling protein necessary for sporulation and developmental gene expression. Nonmotile cells fail to sporulate and to express C-factor-dependent genes, but both defects were rescued by a simple manipulation of cell position that oriented the cells in aligned, parallel groups. A similar pattern of aligned cells normally results from coordinated recruitment of wildtype cells into multicellular aggregates, which later form mature fruiting bodies. It is proposed that directed cell movement establishes critical contacts between adjacent cells, which are required for efficient intercellular C-factor transmission.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kim, S K -- Kaiser, D -- AGO 2908/AG/NIA NIH HHS/ -- New York, N.Y. -- Science. 1990 Aug 24;249(4971):926-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, Stanford University School of Medicine, CA 94305.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2118274" target="_blank"〉PubMed〈/a〉
    Keywords: Bacterial Proteins ; Cell Differentiation ; Cell Division ; Cell Movement ; Kinetics ; Morphogenesis ; Myxococcales/*growth & development/physiology/ultrastructure ; Spores, Bacterial/physiology
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  • 58
    Publication Date: 1990-09-14
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kim, Y C -- Grable, J C -- Love, R -- Greene, P J -- Rosenberg, J M -- GM25671/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Sep 14;249(4974):1307-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Sciences, University of Pittsburgh, PA 15260.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2399465" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Computer Graphics ; Crystallization ; DNA-Binding Proteins ; *Deoxyribonuclease EcoRI ; Methods ; Models, Molecular ; Molecular Sequence Data ; Oligonucleotides ; Protein Conformation ; X-Ray Diffraction
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  • 59
    Publication Date: 1990-12-07
    Description: A series of dipyridodiazepinones have been shown to be potent inhibitors of human immunodeficiency virus-1 (HIV-1) reverse transcriptase (RT). One compound, BI-RG-587, had a Ki of 200 nanomolar for inhibition of HIV-1 RT that was noncompetitive with respect to deoxyguanosine triphosphate. BI-RG-587 was specific for HIV-1 RT, having no effect on feline and simian RT or any mammalian DNA polymerases. BI-RG-587 inhibited HIV-1 replication in vitro as demonstrated by in situ hybridization, inhibition of protein p24 production, and the lack of syncytia formation in cultured human T cell lines and freshly isolated human peripheral blood lymphocytes. Cytotoxicity studies of BI-RG-587 on human cells showed a high therapeutic index (greater than 8000) in culture.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Merluzzi, V J -- Hargrave, K D -- Labadia, M -- Grozinger, K -- Skoog, M -- Wu, J C -- Shih, C K -- Eckner, K -- Hattox, S -- Adams, J -- HB 67027/HB/NHLBI NIH HHS/ -- HL 42257/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1990 Dec 7;250(4986):1411-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, CT 06877.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1701568" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antiviral Agents/*pharmacology ; Cell Line ; HIV-1/*drug effects/enzymology/physiology ; Humans ; Kinetics ; Molecular Structure ; Nevirapine ; Nucleic Acid Synthesis Inhibitors ; Pyridines/chemical synthesis/*pharmacology ; *Reverse Transcriptase Inhibitors ; Virus Replication/*drug effects
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  • 60
    Publication Date: 1990-10-05
    Description: To facilitate functional and mechanistic studies of receptor-G protein interactions, [corrected] the human beta 2-adrenergic receptor (h beta-AR) has been expressed in Saccharomyces cerevisiae. This was achieved by placing a modified h beta-AR gene under control of the galactose-inducible GAL1 promoter. After induction by galactose, functional h beta-AR was expressed at a concentration several hundred times as great as that found in any human tissue. As determined from competitive ligand binding experiments, h beta-AR expressed in yeast displayed characteristic affinities, specificity, and stereoselectivity. Partial activation of the yeast pheromone response pathway by beta-adrenergic receptor agonists was achieved in cells coexpressing h beta-AR and a mammalian G protein (Gs) alpha subunit-demonstrating that these components can couple to each other and to downstream effectors when expressed in yeast. This in vivo reconstitution system provides a new approach for examining ligand binding and G protein coupling to cell surface receptors.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉King, K -- Dohlman, H G -- Thorner, J -- Caron, M G -- Lefkowitz, R J -- GM21841/GM/NIGMS NIH HHS/ -- HL16037/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1990 Oct 5;250(4977):121-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Medicine (Cardiology), Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2171146" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Base Sequence ; Cell Membrane/physiology ; GTP-Binding Proteins/genetics/*physiology ; Gene Expression ; Humans ; Iodocyanopindolol ; Kinetics ; Macromolecular Substances ; Molecular Sequence Data ; Pindolol/analogs & derivatives/metabolism ; Plasmids ; Promoter Regions, Genetic ; Receptors, Adrenergic, beta/genetics/metabolism/*physiology ; Recombinant Fusion Proteins/metabolism ; Restriction Mapping ; Saccharomyces cerevisiae/genetics/*physiology ; *Signal Transduction
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  • 61
    Publication Date: 1990-02-23
    Description: Ras proteins participate as a molecular switch in the early steps of the signal transduction pathway that is associated with cell growth and differentiation. When the protein is in its GTP complexed form it is active in signal transduction, whereas it is inactive in its GDP complexed form. A comparison of eight three-dimensional structures of ras proteins in four different crystal lattices, five with a nonhydrolyzable GTP analog and three with GDP, reveals that the "on" and "off" states of the switch are distinguished by conformational differences that span a length of more than 40 A, and are induced by the gamma-phosphate. The most significant differences are localized in two regions: residues 30 to 38 (the switch I region) in the second loop and residues 60 to 76 (the switch II region) consisting of the fourth loop and the short alpha-helix that follows the loop. Both regions are highly exposed and form a continuous strip on the molecular surface most likely to be the recognition sites for the effector and receptor molecule(or molecules). The conformational differences also provide a structural basis for understanding the biological and biochemical changes of the proteins due to oncogenic mutations, autophosphorylation, and GTP hydrolysis, and for understanding the interactions with other proteins.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Milburn, M V -- Tong, L -- deVos, A M -- Brunger, A -- Yamaizumi, Z -- Nishimura, S -- Kim, S H -- CA45593/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1990 Feb 23;247(4945):939-45.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of California, Berkeley.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2406906" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Crystallization ; Crystallography ; Guanosine Diphosphate/metabolism ; Guanosine Triphosphate/metabolism ; Humans ; Models, Molecular ; Molecular Structure ; Protein Conformation ; Proto-Oncogene Proteins/*metabolism ; Proto-Oncogene Proteins p21(ras) ; *Signal Transduction ; Structure-Activity Relationship
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  • 62
    Publication Date: 1990-09-21
    Description: Ribonuclease H digests the RNA strand of duplex RNA.DNA hybrids into oligonucleotides. This activity is indispensable for retroviral infection and is involved in bacterial replication. The ribonuclease H from Escherichia coli is homologous with the retroviral proteins. The crystal structure of the E. coli enzyme reveals a distinctive alpha-beta tertiary fold. Analysis of the molecular model implicates a carboxyl triad in the catalytic mechanism and suggests a likely mode for the binding of RNA.DNA substrates. The structure was determined by the method of multiwavelength anomalous diffraction (MAD) with the use of synchrotron data from a crystal of the recombinant selenomethionyl protein.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yang, W -- Hendrickson, W A -- Crouch, R J -- Satow, Y -- GM 34102/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Sep 21;249(4975):1398-405.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2169648" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Computer Graphics ; *Endoribonucleases/genetics ; Escherichia coli/enzymology ; Models, Molecular ; Molecular Sequence Data ; Protein Conformation ; Recombinant Proteins ; Ribonuclease H ; *Selenium ; *Selenomethionine ; Sequence Homology, Nucleic Acid ; X-Ray Diffraction/methods
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  • 63
    Publication Date: 1990-08-31
    Description: The isocitrate dehydrogenase of Escherichia coli is regulated by covalent modification at the active site rather than, as expected, at an allosteric site. As a means of evaluating the mechanism of regulation, the kinetics of the substrate, 2R,3S-isocitrate, and a substrate analog, 2R-malate, were compared for the native, phosphorylated, and mutant enzymes. Phosphorylation decreases activity by more than a factor of 10(6) for the true substrate, but causes minor changes in the activity of the substrate analog. The kinetic results indicate that electrostatic repulsion and steric hindrance between the phosphoryl moiety and the gamma carboxyl group of 2R,3S-isocitrate are the major causes of the inactivation, with a lesser contribution from the loss of a hydrogen bond.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Dean, A M -- Koshland, D E Jr -- New York, N.Y. -- Science. 1990 Aug 31;249(4972):1044-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular and Cell Biology, University of California, Berkeley 94720.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2204110" target="_blank"〉PubMed〈/a〉
    Keywords: Allosteric Site ; Amino Acid Sequence ; Binding Sites ; Escherichia coli/*enzymology/genetics ; Isocitrate Dehydrogenase/genetics/*metabolism ; Models, Molecular ; Mutation ; Protein Conformation
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  • 64
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-08-31
    Description: Major histocompatibility complex (MHC) molecules are exposed to large quantities of self and nonself antigens. It is not known what fraction of MHC molecules needs to be occupied by antigen to induce a T cell response. A quantitative study of naturally processed antigen indicated that T cells could be activated when only 0.03 percent of the total I-Ed purified from antigen-presenting cells (APCs) was occupied with antigen. B cells and macrophages processed hen egg lysozyme (HEL) with different efficiencies, but similar degrees of occupancy were required for T cell stimulation. Higher occupancy was needed for I-Ed-transfected L cells, possibly reflecting the requirement for other accessory molecules for efficient APC-T cell interaction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Demotz, S -- Grey, H M -- Sette, A -- AI 09758/AI/NIAID NIH HHS/ -- AI 18634/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1990 Aug 31;249(4972):1028-30.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Cytel Corporation, La Jolla, CA 92037.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2118680" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antigen-Presenting Cells/*immunology ; B-Lymphocytes/immunology ; Cell Line ; Genes, MHC Class II ; Histocompatibility Antigens Class II/*immunology ; Kinetics ; *Lymphocyte Activation ; Lymphoma ; Macrophages/immunology ; Muramidase/immunology ; T-Lymphocytes/*immunology ; Transfection
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  • 65
    Publication Date: 1990-09-28
    Description: In the central nervous system (CNS), the principal mediators of fast synaptic excitatory neurotransmission are L-glutamate-gated ion channels that are responsive to the glutamate agonist alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA). In each member of a family of four abundant AMPA receptors, a small segment preceding the predicted fourth transmembrane region has been shown to exist in two versions with different amino acid sequences. These modules, designated "flip" and "flop," are encoded by adjacent exons of the receptor genes and impart different pharmacological and kinetic properties on currents evoked by L-glutamate or AMPA, but not those evoked by kainate. For each receptor, the alternatively spliced messenger RNAs show distinct expression patterns in rat brain, particularly in the CA1 and CA3 fields of the hippocampus. These results identify a switch in the molecular and functional properties of glutamate receptors operated by alternative splicing.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sommer, B -- Keinanen, K -- Verdoorn, T A -- Wisden, W -- Burnashev, N -- Herb, A -- Kohler, M -- Takagi, T -- Sakmann, B -- Seeburg, P H -- New York, N.Y. -- Science. 1990 Sep 28;249(4976):1580-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Molecular Neuroendocrinology, Center for Molecular Biology, University of Heidelberg, F.R.G.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1699275" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Base Sequence ; Brain/*metabolism ; DNA/genetics ; Exons ; Genomic Library ; Glutamates/*metabolism/pharmacology ; Ibotenic Acid/*analogs & derivatives/metabolism/pharmacology ; Ion Channels/*physiology ; Kinetics ; Molecular Sequence Data ; Oligonucleotide Probes ; Organ Specificity ; *RNA Splicing ; RNA, Messenger/*genetics ; Rats ; Receptors, AMPA ; Receptors, Glutamate ; Receptors, Neurotransmitter/drug effects/*genetics/physiology ; Recombinant Proteins/metabolism ; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid
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  • 66
    Publication Date: 1990-12-07
    Description: The polymerization of actin filaments is involved in growth, movement, and cell division. It has been shown that actin polymerization is controlled by gelsolin, whose interactions with actin are activated by calcium ion (Ca2+) and inhibited by membrane polyphosphoinositides (PPI). A smaller Ca2(+)- and PPI-regulated protein, gCap39, which has 49% sequence identity with gelsolin, has been identified by cDNA cloning and protein purification. Like gelsolin, gCap39 binds to the fast-growing (+) end of actin filaments. However, gCap39 does not sever actin filaments and can respond to Ca2+ and PPI transients independently, under conditions in which gelsolin is ineffective. The coexistence of gCap39 with gelsolin should allow precise regulation of actin assembly at the leading edge of the cell.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yu, F X -- Johnston, P A -- Sudhof, T C -- Yin, H L -- HL 29113/HL/NHLBI NIH HHS/ -- HL 39644/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1990 Dec 7;250(4986):1413-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology, University of Texas Southwestern Medical Center, Dallas 75235-9040.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2255912" target="_blank"〉PubMed〈/a〉
    Keywords: Actins/*metabolism ; Amino Acid Sequence ; Animals ; Cell Line ; DNA/genetics/isolation & purification ; Gene Library ; Humans ; Kidney/metabolism ; Kinetics ; Macrophages/metabolism ; Mice ; Microfilament Proteins/genetics/isolation & purification/*metabolism ; Molecular Sequence Data ; *Nuclear Proteins ; Sequence Homology, Nucleic Acid
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  • 67
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-12-21
    Description: Voltage-activated calcium channels open and close, or gate, according to molecular transition rates that are regulated by transmembrane voltage and neurotransmitters. Here evidence for the control of gating by calcium was found in electrophysiological records of single, L-type calcium channels in heart cells. Conditional open probability analysis revealed that calcium entry during the opening of a single channel produces alterations in gating transition rates that evolve over the course of hundreds of milliseconds. Such alteration of calcium-channel gating by entry of a favored permeant ion provides a mechanism for the short-term modulation of single-ion channels.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yue, D T -- Backx, P H -- Imredy, J P -- 5-T32-GM07057/GM/NIGMS NIH HHS/ -- R29-HL43307/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1990 Dec 21;250(4988):1735-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2176745" target="_blank"〉PubMed〈/a〉
    Keywords: 8-Bromo Cyclic Adenosine Monophosphate/pharmacology ; Animals ; Calcium/*metabolism/pharmacology ; Calcium Channels/drug effects/*physiology ; Guinea Pigs ; Heart/*physiology ; In Vitro Techniques ; *Ion Channel Gating/drug effects ; Kinetics ; Membrane Potentials/drug effects ; Probability ; Ventricular Function
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  • 68
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-02-23
    Description: The atrionatriuretic peptide (ANP) is released from atrial cells in response to increased extracellular fluid volume and reduces sodium absorption by the kidney, thus reducing the blood volume. In this report, ANP suppressed the calcium and sodium currents in rat and guinea pig ventricular myocytes. The suppression of sodium current was caused by enhanced permeability of the sodium channel to calcium without significant changes in the kinetics or the tetrodotoxin sensitivity of the channel. Thus, ANP may regulate the sodium channel by altering its cationic selectivity site to calcium, thereby repressing the sodium current. The suppression of sodium and calcium channels and the resultant depressed excitability of the atrial cells may help to regulate ANP secretion.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sorbera, L A -- Morad, M -- HL16152/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1990 Feb 23;247(4945):969-73.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology, University of Pennsylvania, Philadelphia 19104-6085.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2154853" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Atrial Natriuretic Factor/*pharmacology ; Calcium/metabolism ; Calcium Channels/*metabolism ; Electric Conductivity ; Guinea Pigs ; Heart Ventricles ; Kinetics ; Myocardium/*metabolism ; Permeability ; Rats ; Sodium Channels/drug effects/*metabolism ; Tetrodotoxin/pharmacology
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  • 69
    Publication Date: 1990-12-21
    Description: The progesterone receptor (PR) in the chicken oviduct is a phosphoprotein that regulates gene transcription in the presence of progesterone. Treatment with progesterone in vivo stimulates phosphorylation of the progesterone receptor. With transient transfection assays, the present work has tested whether phosphorylation participates in the regulation of PR-mediated transcription. Treatment with 8-bromo-cyclic adenosine monophosphate (8-Br cAMP), a stimulator of cAMP-dependent protein kinase [protein kinase A (PKA)], mimicked progesterone-dependent, receptor-mediated transcription in the absence of progesterone. Inhibition of PKA blocked hormone action. Treatment with okadaic acid, an inhibitor of protein phosphatases 1 and 2A, stimulated transcription in a manner similar to that of progesterone. These observations suggest that phosphorylation of the PR or other proteins in the transcription complex can modulate PR-mediated transcription in vivo.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Denner, L A -- Weigel, N L -- Maxwell, B L -- Schrader, W T -- O'Malley, B W -- HD-07857/HD/NICHD NIH HHS/ -- HD-22061/HD/NICHD NIH HHS/ -- New York, N.Y. -- Science. 1990 Dec 21;250(4988):1740-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cell Biology, Baylor College of Medicine, Houston, TX 77030.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2176746" target="_blank"〉PubMed〈/a〉
    Keywords: 8-Bromo Cyclic Adenosine Monophosphate/pharmacology ; Animals ; Cell Line ; Chickens ; Female ; Gene Expression Regulation ; Kinetics ; Oviducts/metabolism ; Phosphoprotein Phosphatases/antagonists & inhibitors ; Phosphorylation ; Progesterone/*pharmacology ; Receptors, Progesterone/*metabolism ; *Transcription, Genetic/drug effects ; Transfection
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  • 70
    Publication Date: 1990-08-03
    Description: A two-fold (C2) symmetric inhibitor of the protease of human immunodeficiency virus type-1 (HIV-1) has been designed on the basis of the three-dimensional symmetry of the enzyme active site. The symmetric molecule inhibited both protease activity and acute HIV-1 infection in vitro, was at least 10,000-fold more potent against HIV-1 protease than against related enzymes, and appeared to be stable to degradative enzymes. The 2.8 angstrom crystal structure of the inhibitor-enzyme complex demonstrated that the inhibitor binds to the enzyme in a highly symmetric fashion.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Erickson, J -- Neidhart, D J -- VanDrie, J -- Kempf, D J -- Wang, X C -- Norbeck, D W -- Plattner, J J -- Rittenhouse, J W -- Turon, M -- Wideburg, N -- AI 27220/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1990 Aug 3;249(4968):527-33.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Computer-Assisted Molecular Design, Abbott Laboratories, Abbott Park, IL 60064.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2200122" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Drug Design ; Endopeptidases/*metabolism ; Gene Products, pol/*metabolism ; HIV Protease ; HIV-1/*enzymology ; Kinetics ; Models, Molecular ; Molecular Sequence Data ; Protease Inhibitors/*pharmacology ; Protein Conformation ; Sugar Alcohols/*pharmacology ; Valine/*analogs & derivatives/pharmacology
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 71
    Publication Date: 1990-10-19
    Description: U6 is one of the five small nuclear RNA's (snRNA's) that are required for splicing of nuclear precursor messenger RNA (pre-mRNA). The size and sequence of U6 RNA are conserved among organisms as diverse as yeast and man, and so it has been proposed that U6 RNA functions as a catalytic element in splicing. A procedure for in vitro reconstitution of functional yeast U6 small nuclear ribonucleoproteins (snRNP's) with synthetic U6 RNA was applied in an attempt to elucidate the function of yeast U6 RNA. Two domains in U6 RNA were identified, each of which is required for in vitro splicing. Single nucleotide substitutions in these two domains block splicing either at the first or the second step. Invariably, U6 RNA mutants that block the first step of splicing do not enter the spliceosome. On the other hand, those that block the second step of splicing form a spliceosome but block cleavage at the 3' splice site of the intron. In both domains, the positions of base changes that block the second step of splicing correspond exactly to the site of insertion of pre-mRNA-type introns into the U6 gene of two yeast species, providing a possible explanation for the mechanism of how these introns originated and adding further evidence for the proposed catalytic role of U6 RNA.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Fabrizio, P -- Abelson, J -- GM 32637/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Oct 19;250(4979):404-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉California Institute of Technology, Division of Biology, Pasadena 91125.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2145630" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Cell Nucleus/*metabolism ; Introns ; Models, Molecular ; Molecular Sequence Data ; Mutation ; Nucleic Acid Conformation ; RNA Precursors/*genetics ; *RNA Splicing ; RNA, Small Nuclear/*genetics/metabolism ; Ribonucleoproteins/metabolism ; Ribonucleoproteins, Small Nuclear ; Saccharomyces cerevisiae/genetics ; Schizosaccharomyces/*genetics
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  • 72
    Publication Date: 1990-06-29
    Description: The presence of endothelin, a vasoconstrictor peptide, in the hypothalamus and posterior pituitary suggests that it also regulates neural and other nonvascular target cells. In pituitary gonadotrophs, low doses of endothelin evoked oscillations in the intracellular calcium concentration, and high doses induced a biphasic calcium response. Mobilization of intracellular calcium predominated during the spike phase of the calcium response to endothelin, whereas calcium entry through dihydropyridine-sensitive channels contributed to both the spike and plateau phases of the calcium response. Endothelin was a potent as hypothalamic gonadotropin-releasing hormone (GnRH) in stimulation of gonadotropin release in perifused pituitary cells. Endothelin bound specifically to pituitary cells with a dissociation constant of 70 picomolar, and induced rapid formation of inositol trisphosphate and diacyglycerol. Although intracellular calcium concentration and gonadotropin secretory responses to endothelin were independent to the GnRH receptor, endothelin and GnRH appeared to have a common signal transduction mechanism. These observations suggest that endothelin can act as a neuropeptide to regulate anterior pituitary function.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stojilkovic, S S -- Merelli, F -- Iida, T -- Krsmanovic, L Z -- Catt, K J -- New York, N.Y. -- Science. 1990 Jun 29;248(4963):1663-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Endocrinology and Reproduction Research Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2163546" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Calcium/*metabolism ; Cells, Cultured ; Cytosol/metabolism ; Endothelins ; Endothelium, Vascular ; Female ; Follicle Stimulating Hormone/*secretion ; Gonadotropin-Releasing Hormone/pharmacology ; Kinetics ; Luteinizing Hormone/*secretion ; Male ; Nifedipine/pharmacology ; Orchiectomy ; Peptides/metabolism/*pharmacology ; Pituitary Gland, Anterior/drug effects/*metabolism/secretion ; Rats ; Rats, Inbred Strains ; Receptors, Cell Surface/metabolism ; Receptors, Endothelin ; Reference Values
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  • 73
    Publication Date: 1990-08-31
    Description: Three closely related genes, GluR1, GluR2, and GluR3, encode receptor subunits for the excitatory neurotransmitter glutamate. The proteins encoded by the individual genes form homomeric ion channels in Xenopus oocytes that are sensitive to glutamatergic agonists such as kainate and quisqualate but not to N-methyl-D-aspartate, indicating that binding sites for kainate and quisqualate exist on single receptor polypeptides. In addition, kainate-evoked conductances are potentiated in oocytes expressing two or more of the cloned receptor subunits. Electrophysiological responses obtained with certain subunit combinations show agonist profiles and current-voltage relations that are similar to those obtained in vivo. Finally, in situ hybridization histochemistry reveals that these genes are transcribed in shared neuroanatomical loci. Thus, as with gamma-aminobutyric acid, glycine, and nicotinic acetylcholine receptors, native kainate-quisqualate-sensitive glutamate receptors form a family of heteromeric proteins.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Boulter, J -- Hollmann, M -- O'Shea-Greenfield, A -- Hartley, M -- Deneris, E -- Maron, C -- Heinemann, S -- NS11549/NS/NINDS NIH HHS/ -- NS28709/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1990 Aug 31;249(4972):1033-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, San Diego, CA 92138.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2168579" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Cloning, Molecular ; Gene Expression ; Glutamates/metabolism ; Hippocampus/metabolism ; Kinetics ; Macromolecular Substances ; Membrane Potentials ; Molecular Sequence Data ; *Multigene Family ; Oocytes/physiology ; Rats ; Receptors, Glutamate ; Receptors, Neurotransmitter/*genetics/physiology ; Sequence Homology, Nucleic Acid ; Transcription, Genetic
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  • 74
    Publication Date: 1990-11-30
    Description: Phospholipase C-gamma 1 (PLC-gamma 1), an isozyme of the phosphoinositide-specific phospholipase C family, which occupies a central role in hormonal signal transduction pathways, is an excellent substrate for the epidermal growth factor (EGF) receptor tyrosine kinase. Epidermal growth factor elicits tyrosine phosphorylation of PLC-gamma 1 and phosphatidylinositol 4,5-bisphosphate hydrolysis in various cell lines. The ability of tyrosine phosphorylation to activate the catalytic activity of PLC-gamma 1 was tested. Tyrosine phosphorylation in intact cells or in vitro increased the catalytic activity of PLC-gamma 1. Also, treatment of EGF-activated PLC-gamma 1 with a tyrosine-specific phosphatase substantially decreased the catalytic activity of PLC-gamma 1. These results suggest that the EGF-stimulated formation of inositol 1,4,5-trisphosphate and diacylglycerol in intact cells results, at least in part, from catalytic activation of PLC-gamma 1 through tyrosine phosphorylation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Nishibe, S -- Wahl, M I -- Hernandez-Sotomayor, S M -- Tonks, N K -- Rhee, S G -- Carpenter, G -- CA43720/CA/NCI NIH HHS/ -- GMO7347/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Nov 30;250(4985):1253-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1700866" target="_blank"〉PubMed〈/a〉
    Keywords: Catalysis ; Diglycerides/metabolism ; Enzyme Activation/drug effects ; Epidermal Growth Factor/pharmacology ; Immunosorbent Techniques ; Inositol 1,4,5-Trisphosphate/metabolism ; Isoenzymes/*metabolism ; Kinetics ; Phosphatidylinositol 4,5-Diphosphate ; Phosphatidylinositol Diacylglycerol-Lyase ; Phosphatidylinositols/metabolism ; Phosphoric Diester Hydrolases/*metabolism ; Phosphorylation ; Phosphotyrosine ; Protein-Tyrosine Kinases/metabolism ; Receptor, Epidermal Growth Factor ; Signal Transduction ; Tyrosine/*analogs & derivatives/metabolism
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  • 75
    Publication Date: 1990-06-29
    Description: Platelet-derived growth factor (PDGF) induction of DNA synthesis is believed to involve activation of phospholipase C (PLC) and subsequent accumulation of inositol 1,4,5-triphosphate [I(1,4,5)P3], increase in intracellular Ca2+, activation of protein kinase C (PKC), and receptor down regulation. Generation of these events is triggered by the tyrosine protein kinase (TPK) activity of the PDGF receptor. The TPK inhibitor genistein blocked PDGF induction of these events, including DNA synthesis, with the exception of receptor down regulation. PDGF-induced phosphotyrosine phosphorylations, including receptor autophosphorylation, were inhibited by genistein. Removal of genistein and PDGF resulted in DNA synthesis without the occurrence of PLC activation. These findings indicate that these early events, with the exception of receptor down regulation, are not necessary for PDGF-induced DNA synthesis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hill, T D -- Dean, N M -- Mordan, L J -- Lau, A F -- Kanemitsu, M Y -- Boynton, A L -- CA 2942/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1990 Jun 29;248(4963):1660-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Cancer Research Center of Hawaii, University of Hawaii, Honolulu 96813.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2163545" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Calcium/metabolism ; Cells, Cultured ; Chlorides/pharmacology ; DNA Replication/*drug effects ; Dimethyl Sulfoxide/pharmacology ; Enzyme Activation ; Genistein ; Inositol Phosphates/metabolism ; Isoflavones/pharmacology ; Kinetics ; Lithium/pharmacology ; Lithium Chloride ; Mice ; Phosphatidylinositol 4,5-Diphosphate ; Phosphatidylinositols/metabolism ; Phosphorylation ; Platelet-Derived Growth Factor/*pharmacology ; Protein Kinase C/metabolism ; Protein-Tyrosine Kinases/metabolism ; Type C Phospholipases/*metabolism
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  • 76
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-12-07
    Description: Efficient transport of class I major histocompatibility complex molecules to the cell surface requires association of the class I heavy chain with endogenous peptide and the class I light chain, beta 2-microglobulin (beta 2M). A mutant cell line deficient in beta 2M transports low amounts of nonpeptide-associated heavy chains to the cell surface that can associate with exogenously provided beta 2M and synthetic peptide antigens. Normal beta 2M-sufficient cells grown in serum-free media devoid of beta 2M also require an exogenous source of beta 2M to efficiently bind synthetic peptide. Thus, class I molecules on normal cells do not spontaneously bind or exchange peptides.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Vitiello, A -- Potter, T A -- Sherman, L A -- AI-25280/AI/NIAID NIH HHS/ -- CA-25803/CA/NCI NIH HHS/ -- CA-49394/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1990 Dec 7;250(4986):1423-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Cytel Corporation, La Jolla, CA 92037.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2124002" target="_blank"〉PubMed〈/a〉
    Keywords: Abelson murine leukemia virus/genetics ; Animals ; Antibodies ; Biological Transport ; Cell Line ; Cell Membrane/immunology ; Cell Transformation, Neoplastic ; Cytotoxicity, Immunologic ; Histocompatibility Antigens Class I/analysis/*metabolism ; Immunoglobulin Heavy Chains/metabolism ; Kinetics ; Mice ; Mice, Inbred Strains ; T-Lymphocytes, Cytotoxic/immunology ; beta 2-Microglobulin/genetics/*metabolism
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  • 77
    Publication Date: 1990-09-21
    Description: Triosephosphate isomerase (TIM) is used as a model system for the study of how a localized conformational change in a protein structure is produced and related to enzyme reactivity. An 11-residue loop region moves more than 7 angstroms and closes over the active site when substrate binds. The loop acts like a "lid" in that it moves rigidly and is attached by two hinges to the remainder of the protein. The nature of the motion appears to be built into the loop by conserved residues; the hinge regions, in contrast, are not conserved. Results of molecular dynamics calculations confirm the structural analysis and suggest a possible ligand-induced mechanism for loop closure.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Joseph, D -- Petsko, G A -- Karplus, M -- New York, N.Y. -- Science. 1990 Sep 21;249(4975):1425-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Massachusetts Institute of Technology, Cambridge 02139.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2402636" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Carbohydrate Epimerases/*metabolism ; Hydrogen Bonding ; Models, Molecular ; Molecular Sequence Data ; Protein Binding ; *Protein Conformation ; Software ; Triose-Phosphate Isomerase/*metabolism
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  • 78
    Publication Date: 1990-09-21
    Description: The primary structure of lipopolysaccharide binding protein (LBP), a trace plasma protein that binds to the lipid A moiety of bacterial lipopolysaccharides (LPSs), was deduced by sequencing cloned complementary DNA. LBP shares sequence identity with another LPS binding protein found in granulocytes, bactericidal/permeability-increasing protein, and with cholesterol ester transport protein of the plasma. LBP may control the response to LPS under physiologic conditions by forming high-affinity complexes with LPS that bind to monocytes and macrophages, which then secrete tumor necrosis factor. The identification of this pathway for LPS-induced monocyte stimulation may aid in the development of treatments for diseases in which Gram-negative sepsis or endotoxemia are involved.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schumann, R R -- Leong, S R -- Flaggs, G W -- Gray, P W -- Wright, S D -- Mathison, J C -- Tobias, P S -- Ulevitch, R J -- AI 15136/AI/NIAID NIH HHS/ -- AI 25563/AI/NIAID NIH HHS/ -- GM 28485/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Sep 21;249(4975):1429-31.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Immunology, Research Institute of Scripps Clinic, La Jolla, CA 92037.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2402637" target="_blank"〉PubMed〈/a〉
    Keywords: *Acute-Phase Proteins ; Amino Acid Sequence ; Animals ; Base Sequence ; Blood Proteins/*genetics ; Carrier Proteins/*genetics/metabolism ; Gene Library ; Humans ; Kinetics ; Lipid A/metabolism ; Lipopolysaccharides/*metabolism/pharmacology ; Male ; *Membrane Glycoproteins ; Molecular Sequence Data ; Oligonucleotide Probes ; Rabbits ; Sequence Homology, Nucleic Acid ; Sheep ; Staphylococcus aureus ; Tumor Necrosis Factor-alpha/biosynthesis
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  • 79
    Publication Date: 1990-08-03
    Description: Human immunodeficiency virus (HIV) frequently causes neurological dysfunction and is abundantly expressed in the central nervous system (CNS) of acquired immunodeficiency syndrome (AIDS) patients with HIV encephalitis or myelopathy. The virus is found mostly in cells of the monocyte-macrophage lineage within the CNS, but the possibility of infection of other glial cells has been raised. Therefore, the effects of different HIV-1 and HIV-2 strains were studied in primary cultures of adult human brain containing microglial cells, the resident CNS macrophages, and astrocytes. These cultures could be productively infected with macrophage-adapted HIV-1 isolates but not with T lymphocyte-adapted HIV-1 isolates or two HIV-2 isolates. As determined with a triple-label procedure, primary astrocytes did not express HIV gag antigens and remained normal throughout the 3-week course of infection. In contrast, virus replicated in neighboring microglial cells, often leading to their cell fusion and death. The death of microglial cells, which normally serve immune functions in the CNS, may be a key factor in the pathogenesis of AIDS encephalitis or myelopathy.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Watkins, B A -- Dorn, H H -- Kelly, W B -- Armstrong, R C -- Potts, B J -- Michaels, F -- Kufta, C V -- Dubois-Dalcq, M -- New York, N.Y. -- Science. 1990 Aug 3;249(4968):549-53.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Viral and Molecular Pathogenesis, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2200125" target="_blank"〉PubMed〈/a〉
    Keywords: Adult ; Brain/*microbiology ; Cells, Cultured ; Fluorescent Antibody Technique ; HIV-1/pathogenicity/*physiology ; HIV-2/pathogenicity/physiology ; Humans ; Kinetics ; Neuroglia/*microbiology ; Species Specificity ; Virus Replication
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  • 80
    Publication Date: 1990-05-04
    Description: A low molecular weight serine protease inhibitor (TAP) was purified from extracts of the soft tick, Ornithodoros moubata. The peptide is a slow, tight-binding inhibitor, specific for factor Xa (Ki = 0.588 +/- 0.054 nM). The inhibitor also acts as an anticoagulant in several human plasma clotting assays in vitro. Its amino acid sequence (60 residues) has limited homology to the Kunitz-type inhibitors. However, unlike other inhibitors of this class, TAP inhibits only factor Xa. It had no effect at a 300-fold molar excess on factor VIIa, kallikrein, trypsin, chymotrypsin, thrombin, urokinase, plasmin, tissue plasminogen activator, elastase, or Staphylococcus aureus V8 protease. TAP's specificity and size suggest that it may have therapeutic value as an anticoagulant.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Waxman, L -- Smith, D E -- Arcuri, K E -- Vlasuk, G P -- New York, N.Y. -- Science. 1990 May 4;248(4955):593-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Biological Chemistry Department, Merck Sharp & Dohme Research Laboratories, West Point, PA 19486.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2333510" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Arthropod Proteins ; Blood Coagulation Tests ; Chromatography, Gel ; *Factor Xa Inhibitors ; Humans ; Kinetics ; Molecular Sequence Data ; Peptides/*isolation & purification/pharmacology ; Sequence Homology, Nucleic Acid ; Serine Proteinase Inhibitors/*isolation & purification ; Ticks/*analysis
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  • 81
    Publication Date: 1994-06-24
    Description: Two ternary complexes of rat DNA polymerase beta (pol beta), a DNA template-primer, and dideoxycytidine triphosphate (ddCTP) have been determined at 2.9 A and 3.6 A resolution, respectively. ddCTP is the triphosphate of dideoxycytidine (ddC), a nucleoside analog that targets the reverse transcriptase of human immunodeficiency virus (HIV) and is at present used to treat AIDS. Although crystals of the two complexes belong to different space groups, the structures are similar, suggesting that the polymerase-DNA-ddCTP interactions are not affected by crystal packing forces. In the pol beta active site, the attacking 3'-OH of the elongating primer, the ddCTP phosphates, and two Mg2+ ions are all clustered around Asp190, Asp192, and Asp256. Two of these residues, Asp190 and Asp256, are present in the amino acid sequences of all polymerases so far studied and are also spatially similar in the four polymerases--the Klenow fragment of Escherichia coli DNA polymerase I, HIV-1 reverse transcriptase, T7 RNA polymerase, and rat DNA pol beta--whose crystal structures are now known. A two-metal ion mechanism is described for the nucleotidyl transfer reaction and may apply to all polymerases. In the ternary complex structures analyzed, pol beta binds to the DNA template-primer in a different manner from that recently proposed for other polymerase-DNA models.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pelletier, H -- Sawaya, M R -- Kumar, A -- Wilson, S H -- Kraut, J -- CA17374/CA/NCI NIH HHS/ -- ES06839/ES/NIEHS NIH HHS/ -- GM10928/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Jun 24;264(5167):1891-903.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of California, San Diego 92093-0317.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7516580" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Binding Sites ; Crystallization ; Crystallography, X-Ray ; DNA/chemistry/metabolism ; DNA Polymerase I/*chemistry/metabolism ; DNA Primers/*chemistry/metabolism ; DNA-Directed RNA Polymerases/chemistry/metabolism ; Deoxycytosine Nucleotides/*chemistry/metabolism ; Dideoxynucleotides ; HIV Reverse Transcriptase ; Humans ; Hydrogen Bonding ; Models, Molecular ; Molecular Sequence Data ; RNA-Directed DNA Polymerase/chemistry/metabolism ; Rats ; Recombinant Proteins ; Templates, Genetic ; Thymine Nucleotides/chemistry/metabolism ; Viral Proteins ; Zidovudine/analogs & derivatives/chemistry/metabolism
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  • 82
    Publication Date: 1994-04-01
    Description: The crystal structure of a ternary protein complex has been determined at 2.4 angstrom resolution. The complex is composed of three electron transfer proteins from Paracoccus denitrificans, the quinoprotein methylamine dehydrogenase, the blue copper protein amicyanin, and the cytochrome c551i. The central region of the c551i is folded similarly to several small bacterial c-type cytochromes; there is a 45-residue extension at the amino terminus and a 25-residue extension at the carboxyl terminus. The methylamine dehydrogenase-amicyanin interface is largely hydrophobic, whereas the amicyanin-cytochrome interface is more polar, with several charged groups present on each surface. Analysis of the simplest electron transfer pathways between the redox partners points out the importance of other factors such as energetics in determining the electron transfer rates.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chen, L -- Durley, R C -- Mathews, F S -- Davidson, V L -- GM41574/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Apr 1;264(5155):86-90.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8140419" target="_blank"〉PubMed〈/a〉
    Keywords: Bacterial Proteins/*chemistry/metabolism ; Computer Graphics ; Cytochrome c Group/*chemistry/metabolism ; Electron Transport ; Hydrogen Bonding ; *Indolequinones ; Models, Molecular ; Oxidation-Reduction ; Oxidoreductases Acting on CH-NH Group Donors/*chemistry/metabolism ; Paracoccus denitrificans/*chemistry/enzymology ; Protein Conformation ; Protein Folding ; Protein Structure, Secondary ; Quinones/chemistry/metabolism ; Software ; Tryptophan/analogs & derivatives/chemistry/metabolism
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  • 83
    Publication Date: 1994-02-04
    Description: The three-dimensional structure of a catalytic antibody (1F7) with chorismate mutase activity has been determined to 3.0 A resolution as a complex with a transition state analog. The structural data suggest that the antibody stabilizes the same conformationally restricted pericyclic transition state as occurs in the uncatalyzed reaction. Overall shape and charge complementarity between the combining site and the transition state analog dictate preferential binding of the correct substrate enantiomer in a conformation appropriate for reaction. Comparison with the structure of a chorismate mutase enzyme indicates an overall similarity between the catalytic mechanism employed by the two proteins. Differences in the number of specific interactions available for restricting the rotational degrees of freedom in the transition state, and the lack of multiple electrostatic interactions that might stabilize charge separation in this highly polarized metastable species, are likely to account for the observed 10(4) times lower activity of the antibody relative to that of the natural enzymes that catalyze this reaction. The structure of the 1F7 Fab'-hapten complex provides confirmation that the properties of an antibody catalyst faithfully reflect the design of the transition state analog.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Haynes, M R -- Stura, E A -- Hilvert, D -- Wilson, I A -- AI-23498/AI/NIAID NIH HHS/ -- GM-38273/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Feb 4;263(5147):646-52.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, Scripps Research Institute, La Jolla, CA 92037.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8303271" target="_blank"〉PubMed〈/a〉
    Keywords: Antibodies, Catalytic/*chemistry/metabolism ; Bacillus subtilis/enzymology ; Binding Sites ; Binding Sites, Antibody ; Catalysis ; Chorismate Mutase/*chemistry/metabolism ; Chorismic Acid/metabolism ; Crystallization ; Haptens ; Hydrogen Bonding ; Immunoglobulin Fab Fragments/metabolism ; Models, Molecular ; Thermodynamics
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  • 84
    Publication Date: 1994-07-01
    Description: Here it is shown, with the use of protein-protein photocrosslinking, that the carboxyl-terminal region of the alpha subunit of RNA polymerase (RNAP) is in direct physical proximity to the activating region of the catabolite gene activator protein (CAP) in the ternary complex of the lac promoter, RNAP, and CAP. These results strongly support the proposal that transcription activation by CAP involves protein-protein contact between the carboxyl-terminal region of the alpha subunit and the activating region of CAP.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chen, Y -- Ebright, Y W -- Ebright, R H -- GM41376/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Jul 1;265(5168):90-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Rutgers University, New Brunswick, NJ 08855.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8016656" target="_blank"〉PubMed〈/a〉
    Keywords: Azides/metabolism ; Cross-Linking Reagents ; Crystallography, X-Ray ; Cyclic AMP Receptor Protein/chemistry/*metabolism ; DNA-Directed RNA Polymerases/chemistry/*metabolism ; Lac Operon ; Models, Molecular ; *Promoter Regions, Genetic ; Pyridines/metabolism ; *Transcriptional Activation
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  • 85
    Publication Date: 1994-10-21
    Description: The structure of the heterodimeric flavocytochrome c sulfide dehydrogenase from Chromatium vinosum was determined at a resolution of 2.53 angstroms. It contains a glutathione reductase-like flavin-binding subunit and a diheme cytochrome subunit. The diheme cytochrome folds as two domains, each resembling mitochondrial cytochrome c, and has an unusual interpropionic acid linkage joining the two heme groups in the interior of the subunit. The active site of the flavoprotein subunit contains a catalytically important disulfide bridge located above the pyrimidine portion of the flavin ring. A tryptophan, threonine, or tyrosine side chain may provide a partial conduit for electron transfer to one of the heme groups located 10 angstroms from the flavin.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chen, Z W -- Koh, M -- Van Driessche, G -- Van Beeumen, J J -- Bartsch, R G -- Meyer, T E -- Cusanovich, M A -- Mathews, F S -- GM-20530/GM/NIGMS NIH HHS/ -- GM-21277/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Oct 21;266(5184):430-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7939681" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Chromatium/*enzymology ; Computer Graphics ; Crystallography, X-Ray ; Cytochrome c Group/*chemistry ; Electron Transport ; Flavin-Adenine Dinucleotide/metabolism ; Hydrogen Bonding ; Models, Molecular ; Oxidoreductases/*chemistry ; Protein Conformation ; Protein Structure, Secondary
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  • 86
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-05-20
    Description: A predictive rule for protein folding is presented that involves two recurrent glycine-based motifs that cap the carboxyl termini of alpha helices. In proteins, helices that terminated in glycine residues were found predominantly in one of these two motifs. These glycine structures had a characteristic pattern of polar and apolar residues. Visual inspection of known helical sequences was sufficient to distinguish the two motifs from each other and from internal glycines that fail to terminate helices. These glycine motifs--in which the local sequence selects between available structures--represent an example of a stereochemical rule for protein folding.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Aurora, R -- Srinivasan, R -- Rose, G D -- GM 29458/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 May 20;264(5162):1126-30.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8178170" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Glycine/*chemistry ; Hydrogen Bonding ; Models, Molecular ; Molecular Sequence Data ; Mutation ; Oligopeptides/chemistry ; *Protein Folding ; *Protein Structure, Secondary
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  • 87
    Publication Date: 1994-06-03
    Description: Multi-wavelength anomalous diffraction (MAD) has been used to determine the structure of the regulatory enzyme of de novo synthesis of purine nucleotides, glutamine 5-phosphoribosyl-1-pyrophosphate (PRPP) amidotransferase, from Bacillus subtilis. This allosteric enzyme, a 200-kilodalton tetramer, is subject to end product regulation by purine nucleotides. The metalloenzyme from B. subtilis is a paradigm for the higher eukaryotic enzymes, which have been refractory to isolation in stable form. The two folding domains of the polypeptide are correlated with functional domains for glutamine binding and for transfer of ammonia to the substrate PRPP. Eight molecules of the feedback inhibitor adenosine monophosphate (AMP) are bound to the tetrameric enzyme in two types of binding sites: the PRPP catalytic site of each subunit and an unusual regulatory site that is immediately adjacent to each active site but is between subunits. An oxygen-sensitive [4Fe-4S] cluster in each subunit is proposed to regulate protein turnover in vivo and is distant from the catalytic site. Oxygen sensitivity of the cluster is diminished by AMP, which blocks a channel through the protein to the cluster. The structure is representative of both glutamine amidotransferases and phosphoribosyltransferases.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Smith, J L -- Zaluzec, E J -- Wery, J P -- Niu, L -- Switzer, R L -- Zalkin, H -- Satow, Y -- DK-42303/DK/NIDDK NIH HHS/ -- GM-24658/GM/NIGMS NIH HHS/ -- R37 DK042303/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1994 Jun 3;264(5164):1427-33.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Sciences, Purdue University, West Lafayette, IN 47907.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8197456" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Monophosphate/metabolism ; Allosteric Regulation ; Amidophosphoribosyltransferase/*chemistry/metabolism ; Amino Acid Sequence ; Animals ; Bacillus subtilis/*enzymology ; Binding Sites ; Computer Graphics ; Crystallography, X-Ray ; Humans ; Models, Molecular ; Molecular Sequence Data ; Oxygen/pharmacology ; Protein Folding ; Protein Structure, Secondary ; Saccharomyces cerevisiae
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  • 88
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-06-24
    Description: The basic notions of transition state theory have been exploited in the past to generate highly selective catalysts from the vast library of antibody molecules in the immune system. These same ideas were used to isolate an RNA molecule, from a large library of RNAs, that catalyzes the isomerization of a bridged biphenyl. The RNA-catalyzed reaction displays Michaelis-Menten kinetics with a catalytic rate constant (kcat) of 2.8 x 10(-5) per minute and a Michaelis constant (Km) of 542 microM; the reaction is competitively inhibited by the planar transition state analog with an inhibition constant (Ki) value of approximately 7 microM. This approach may provide a general strategy for expanding the scope of RNA catalysis beyond those reactions in which the substrates are nucleic acids or nucleic acid derivatives.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Prudent, J R -- Uno, T -- Schultz, P G -- GM08352A/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Jun 24;264(5167):1924-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of California, Berkeley.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8009223" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Biphenyl Compounds/chemistry/metabolism ; Catalysis ; Kinetics ; Molecular Sequence Data ; Nucleic Acid Conformation ; Nucleic Acid Denaturation ; Polymerase Chain Reaction ; RNA, Catalytic/chemistry/*metabolism ; Stereoisomerism ; Temperature
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  • 89
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-03-11
    Description: Protein tyrosine phosphatases (PTPs) constitute a family of receptor-like and cytoplasmic signal transducing enzymes that catalyze the dephosphorylation of phosphotyrosine residues and are characterized by homologous catalytic domains. The crystal structure of a representative member of this family, the 37-kilodalton form (residues 1 to 321) of PTP1B, has been determined at 2.8 A resolution. The enzyme consists of a single domain with the catalytic site located at the base of a shallow cleft. The phosphate recognition site is created from a loop that is located at the amino-terminus of an alpha helix. This site is formed from an 11-residue sequence motif that is diagnostic of PTPs and the dual specificity phosphatases, and that contains the catalytically essential cysteine and arginine residues. The position of the invariant cysteine residue within the phosphate binding site is consistent with its role as a nucleophile in the catalytic reaction. The structure of PTP1B should serve as a model for other members of the PTP family and as a framework for understanding the mechanism of tyrosine dephosphorylation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Barford, D -- Flint, A J -- Tonks, N K -- CA53840/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1994 Mar 11;263(5152):1397-404.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉W.M. Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, NY 11724.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8128219" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Computer Graphics ; Crystallography, X-Ray ; Humans ; Models, Molecular ; Molecular Sequence Data ; Phosphates/metabolism ; Protein Conformation ; Protein Folding ; Protein Structure, Secondary ; Protein Tyrosine Phosphatases/*chemistry/isolation & purification/metabolism ; Substrate Specificity ; Tungsten Compounds/metabolism
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  • 90
    Publication Date: 1994-08-19
    Description: A small molecule called PD 153035 inhibited the epidermal growth factor (EGF) receptor tyrosine kinase with a 5-pM inhibition constant. The inhibitor was specific for the EGF receptor tyrosine kinase and inhibited other purified tyrosine kinases only at micromolar or higher concentrations. PD 153035 rapidly suppressed autophosphorylation of the EGF receptor at low nanomolar concentrations in fibroblasts or in human epidermoid carcinoma cells and selectively blocked EGF-mediated cellular processes including mitogenesis, early gene expression, and oncogenic transformation. PD 153035 demonstrates an increase in potency over that of other tyrosine kinase inhibitors of four to five orders of magnitude for inhibition of isolated EGF receptor tyrosine kinase and three to four orders of magnitude for inhibition of cellular phosphorylation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Fry, D W -- Kraker, A J -- McMichael, A -- Ambroso, L A -- Nelson, J M -- Leopold, W R -- Connors, R W -- Bridges, A J -- New York, N.Y. -- Science. 1994 Aug 19;265(5175):1093-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Parke-Davis Pharmaceutical Research, Division of Warner-Lambert Company, Ann Arbor, MI 48105.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8066447" target="_blank"〉PubMed〈/a〉
    Keywords: 3T3 Cells ; Animals ; Cell Transformation, Neoplastic/drug effects ; Epidermal Growth Factor/pharmacology ; Fibroblast Growth Factor 2/pharmacology ; Gene Expression/drug effects ; Humans ; Kinetics ; Mice ; Mitosis/drug effects ; Phosphorylation/drug effects ; Platelet-Derived Growth Factor/pharmacology ; Protein-Tyrosine Kinases/antagonists & inhibitors ; Quinazolines/*antagonists & inhibitors ; Receptor, Epidermal Growth Factor/*antagonists & inhibitors ; Tumor Cells, Cultured ; Tyrosine/metabolism
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  • 91
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-09-23
    Description: The functional consequences of single proton transfers occurring in the pore of a cyclic nucleotide-gated channel were observed with patch recording techniques. These results led to three conclusions about the chemical nature of ion binding sites in the conduction pathway: The channel contains two identical titratable sites, even though there are more than two (probably four) identical subunits; the sites are formed by glutamate residues that have a pKa (where K(a) is the acid constant) of 7.6; and protonation of one site does not perturb the pKa of the other. These properties point to an unusual arrangement of carboxyl side-chain residues in the pore of a cation channel.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Root, M J -- MacKinnon, R -- 5 T32 GM083113/GM/NIGMS NIH HHS/ -- GM47400/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Sep 23;265(5180):1852-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Neurobiology, Harvard Medical School, Boston, MA 02115.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7522344" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Binding Sites ; Calcium Channels/metabolism ; Catfishes ; Electric Conductivity ; Hydrogen-Ion Concentration ; Ion Channel Gating ; Ion Channels/chemistry/genetics/*metabolism ; Kinetics ; Molecular Sequence Data ; Mutation ; *Protons ; Sodium/metabolism ; Xenopus
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  • 92
    Publication Date: 1994-09-16
    Description: A reverse protocol for measurements of molecular binding and reactivity by excited-state quenching has been developed in which the quencher, held at a fixed concentration, is titrated by a photoexcitable probe molecule whose decay is monitored. The binding stoichiometries, affinities, and reactivities of the electron-transfer complexes between cytochrome c (Cc) and cytochrome c peroxidase (CcP) were determined over a wide range of ionic strengths (4.5 to 118 millimolar) by the study of photoinduced electron-transfer quenching of the triplet excited state of zinc-substituted Cc (ZnCc) by Fe3+CcP. The 2:1 stoichiometry seen for the binding of Cc to CcP at low ionic strength persists at the physiologically relevant ionic strengths and likely has functional significance. Analysis of the stoichiometric binding and rate constants confirms that one surface domain of CcP binds Cc with a high affinity but with poor electron-transfer quenching of triplet-state ZnCc, whereas a second binds weakly but with a high rate of electron-transfer quenching.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zhou, J S -- Hoffman, B M -- HL13531/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1994 Sep 16;265(5179):1693-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Northwestern University, Evanston, IL 60208-3113.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8085152" target="_blank"〉PubMed〈/a〉
    Keywords: Cytochrome c Group/chemistry/*metabolism ; Cytochrome-c Peroxidase/chemistry/*metabolism ; Electron Transport ; Ferric Compounds ; Kinetics ; Osmolar Concentration ; Oxidation-Reduction ; Zinc
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  • 93
    Publication Date: 1994-01-28
    Description: As changes in synaptic strength are thought to be critical for learning and memory, it would be useful to monitor the activity of individual identified synapses on mammalian central neurons. Calcium imaging of cortical neurons grown in primary culture was used to visualize the activation of individual postsynaptic elements by miniature excitatory synaptic currents elicited by spontaneous quantal release. This approach revealed that the probability of spontaneous activity differed among synapses on the same dendrite. Furthermore, synapses that undergo changes in activity induced by glutamate or phorbol ester treatment were identified.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Murphy, T H -- Baraban, J M -- Wier, W G -- Blatter, L A -- New York, N.Y. -- Science. 1994 Jan 28;263(5146):529-32.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7904774" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Calcium/*metabolism ; Cells, Cultured ; Cerebral Cortex ; Dendrites/*metabolism ; Glutamates/pharmacology ; Glutamic Acid ; Kinetics ; Microelectrodes ; Neuronal Plasticity ; Neurons/*physiology ; Phorbol Esters/pharmacology ; Rats ; Receptors, N-Methyl-D-Aspartate/physiology ; Synapses/*physiology ; *Synaptic Transmission ; Tetrodotoxin/pharmacology
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  • 94
    Publication Date: 1994-12-09
    Description: AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor channels mediate the fast component of excitatory postsynaptic currents in the central nervous system. Site-selective nuclear RNA editing controls the calcium permeability of these channels, and RNA editing at a second site is shown here to affect the kinetic aspects of these channels in rat brain. In three of the four AMPA receptor subunits (GluR-B, -C, and -D), intronic elements determine a codon switch (AGA, arginine, to GGA, glycine) in the primary transcripts in a position termed the R/G site, which immediately precedes the alternatively spliced modules "flip" and "flop." The extent of editing at this site progresses with brain development in a manner specific for subunit and splice form, and edited channels possess faster recovery rates from desensitization.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lomeli, H -- Mosbacher, J -- Melcher, T -- Hoger, T -- Geiger, J R -- Kuner, T -- Monyer, H -- Higuchi, M -- Bach, A -- Seeburg, P H -- New York, N.Y. -- Science. 1994 Dec 9;266(5191):1709-13.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Molecular Neuroendocrinology, University of Heidelberg, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7992055" target="_blank"〉PubMed〈/a〉
    Keywords: Alternative Splicing ; Amino Acid Sequence ; Animals ; Base Sequence ; Brain/embryology/*metabolism ; Cell Nucleus/metabolism ; Exons ; Glutamic Acid/pharmacology ; Glycine/genetics ; Introns ; Kinetics ; Membrane Potentials ; Molecular Sequence Data ; Oocytes ; PC12 Cells ; Patch-Clamp Techniques ; *RNA Editing ; Rats ; Rats, Wistar ; Receptors, AMPA/*genetics/*metabolism ; Recombinant Proteins/metabolism ; Xenopus
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  • 95
    Publication Date: 1994-03-04
    Description: The enzyme acetylcholinesterase generates a strong electrostatic field that can attract the cationic substrate acetylcholine to the active site. However, the long and narrow active site gorge seems inconsistent with the enzyme's high catalytic rate. A molecular dynamics simulation of acetylcholinesterase in water reveals the transient opening of a short channel, large enough to pass a water molecule, through a thin wall of the active site near tryptophan-84. This simulation suggests that substrate, products, or solvent could move through this "back door," in addition to the entrance revealed by the crystallographic structure. Electrostatic calculations show a strong field at the back door, oriented to attract the substrate and the reaction product choline and to repel the other reaction product, acetate. Analysis of the open back door conformation suggests a mutation that could seal the back door and thus test the hypothesis that thermal motion of this enzyme may open multiple routes of access to its active site.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gilson, M K -- Straatsma, T P -- McCammon, J A -- Ripoll, D R -- Faerman, C H -- Axelsen, P H -- Silman, I -- Sussman, J L -- New York, N.Y. -- Science. 1994 Mar 4;263(5151):1276-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of Houston, TX 77204-5641.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8122110" target="_blank"〉PubMed〈/a〉
    Keywords: Acetylcholine/metabolism ; Acetylcholinesterase/*chemistry/metabolism ; Binding Sites ; Catalysis ; Choline/metabolism ; Computer Simulation ; Crystallography, X-Ray ; Electrochemistry ; Models, Molecular ; *Protein Conformation
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  • 96
    Publication Date: 1994-06-10
    Description: Specific protein-ligand interactions are critical for cellular function, and most proteins select their partners with sharp discrimination. However, the oligopeptide-binding protein of Salmonella typhimurium (OppA) binds peptides of two to five amino acid residues without regard to sequence. The crystal structure of OppA reveals a three-domain organization, unlike other periplasmic binding proteins. In OppA-peptide complexes, the ligands are completely enclosed in the protein interior, a mode of binding that normally imposes tight specificity. The protein fulfills the hydrogen bonding and electrostatic potential of the ligand main chain and accommodates the peptide side chains in voluminous hydrated cavities.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tame, J R -- Murshudov, G N -- Dodson, E J -- Neil, T K -- Dodson, G G -- Higgins, C F -- Wilkinson, A J -- New York, N.Y. -- Science. 1994 Jun 10;264(5165):1578-81.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of York, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8202710" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Bacterial Proteins/chemistry/*metabolism ; Binding Sites ; Carrier Proteins/chemistry/*metabolism ; Crystallography, X-Ray ; Hydrogen Bonding ; Ligands ; Lipoproteins/chemistry/*metabolism ; Models, Molecular ; Molecular Sequence Data ; Molecular Weight ; Oligopeptides/chemistry/*metabolism ; Protein Conformation ; Protein Structure, Secondary
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  • 97
    Publication Date: 1994-09-30
    Description: Nucleotide sequence information derived from DNA segments of the human and other genomes is accumulating rapidly. However, it frequently proves difficult to use such short DNA segments to identify clones in genomic libraries or fragments in blots of the whole genome or for in situ analysis of chromosomes. Oligonucleotide probes, consisting of two target-complementary segments, connected by a linker sequence, were designed. Upon recognition of the specific nucleic acid molecule the ends of the probes were joined through the action of a ligase, creating circular DNA molecules catenated to the target sequence. These probes thus provide highly specific detection with minimal background.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Nilsson, M -- Malmgren, H -- Samiotaki, M -- Kwiatkowski, M -- Chowdhary, B P -- Landegren, U -- New York, N.Y. -- Science. 1994 Sep 30;265(5181):2085-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Beijer Laboratory, Department of Medical Genetics, Biomedical Center, Uppsala, Sweden.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7522346" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Cells, Cultured ; Chromosomes, Human, Pair 12 ; Cystic Fibrosis Transmembrane Conductance Regulator ; DNA/*analysis ; DNA, Circular/*analysis ; Genetic Vectors ; Humans ; In Situ Hybridization ; Lymphocytes ; Membrane Proteins/genetics ; Models, Molecular ; Molecular Sequence Data ; Nucleic Acid Conformation ; *Oligonucleotide Probes/chemistry ; Repetitive Sequences, Nucleic Acid ; Templates, Genetic
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  • 98
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-02-18
    Description: Molecular chaperones of the Hsp70 type transiently sequester unfolded segments of proteins and promote their correct folding. Target peptides were labeled with an environmentally sensitive fluorophore so that their binding to the molecular chaperone DnaK of Escherichia coli could be followed in real time. The two-step process was characterized by relaxation times of 27 seconds and 200 seconds with 2 microM DnaK and 0.1 microM ligand at 25 degrees C. In the presence of adenosine triphosphate, the formation of the complex was greatly accelerated and appeared to be a single-exponential process with a relaxation time of 0.4 second. The binding-release cycle of DnaK thus occurs in the time range of polypeptide chain elongation and folding and is too fast to be stoichiometrically coupled to the adenosine triphosphatase activity of the chaperone (turnover number, 0.13 per minute at 30 degrees C).〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schmid, D -- Baici, A -- Gehring, H -- Christen, P -- New York, N.Y. -- Science. 1994 Feb 18;263(5149):971-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Biochemisches Institut, Universitat Zurich, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8310296" target="_blank"〉PubMed〈/a〉
    Keywords: 2-Naphthylamine/analogs & derivatives ; Adenosine Triphosphatases/metabolism ; Adenosine Triphosphate/analogs & derivatives/pharmacology ; Amino Acid Sequence ; Aspartate Aminotransferases/metabolism ; Bacterial Proteins/*metabolism ; Binding Sites ; Enzyme Precursors/metabolism ; *Escherichia coli Proteins ; Fluorescent Dyes ; *HSP70 Heat-Shock Proteins ; Heat-Shock Proteins/*metabolism ; Kinetics ; Molecular Sequence Data ; Peptide Fragments/*metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 99
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-03-04
    Description: Physical inclusion of small molecules in larger structural lattices is well known in the crystalline state and is a common feature of the chemistry of zeolites. In the liquid state, a variety of synthetic macrocyclic molecules are available to complex and contain smaller guest species. An alternative strategy for binding is explored: assembly of cavity-forming structures from small subunits. Encapsulation of small guest molecules such as methane can be achieved with a synthetic structure that assembles reversibly through hydrogen bonding.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Branda, N -- Wyler, R -- Rebek, J Jr -- New York, N.Y. -- Science. 1994 Mar 4;263(5151):1267-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Massachusetts Institute of Technology, Cambridge 02139.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8122107" target="_blank"〉PubMed〈/a〉
    Keywords: Benzyl Compounds/chemistry ; Chemistry, Physical ; Chloroform ; Hydrogen Bonding ; Imidazoles/chemistry ; Magnetic Resonance Spectroscopy ; Methane/*chemistry ; Models, Molecular ; Molecular Conformation ; Molecular Structure ; Physicochemical Phenomena ; Polymers/*chemistry ; Temperature ; Thermodynamics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 100
    Publication Date: 1994-08-05
    Description: The high-mobility group protein 14 (HMG-14) is a non-histone chromosomal protein that is preferentially associated with transcriptionally active chromatin. To assess the effect of HMG-14 on transcription by RNA polymerase II, in vivo-assembled chromatin with elevated amounts of HMG-14 was obtained. Here it is shown that HMG-14 enhanced transcription on chromatin templates but not on DNA templates. This protein stimulated the rate of elongation by RNA polymerase II but not the level of initiation of transcription. These findings suggest that the association of HMG-14 with nucleosomes is part of the cellular process involved in the generation of transcriptionally active chromatin.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ding, H F -- Rimsky, S -- Batson, S C -- Bustin, M -- Hansen, U -- GM-36667/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Aug 5;265(5173):796-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Molecular Genetics, Dana-Farber Cancer Institute, Boston, MA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8047885" target="_blank"〉PubMed〈/a〉
    Keywords: Chromatin/metabolism ; HeLa Cells ; High Mobility Group Proteins/*physiology ; Humans ; Kinetics ; RNA Polymerase II/*metabolism ; Simian virus 40/genetics ; Templates, Genetic ; Transcription, Genetic/*physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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