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  • Kinetics  (158)
  • American Association for the Advancement of Science (AAAS)  (158)
  • American Chemical Society (ACS)
  • 1985-1989  (158)
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  • American Association for the Advancement of Science (AAAS)  (158)
  • American Chemical Society (ACS)
  • Springer  (23)
  • Wiley-Blackwell  (1)
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Year
  • 1
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-05-05
    Description: Tumor promoters may bring about events that lead to neoplastic transformation by inducing specific promotion-relevant effector genes. Functional activation of the transacting transcription factor AP-1 by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) may play an essential role in this process. Clonal genetic variants of mouse epidermal JB6 cells that are genetically susceptible (P+) or resistant (P-) to promotion of transformation by TPA were transfected with 3XTRE-CAT, a construct that has AP-1 cis-enhancer sequences attached to a reporter gene encoding chloramphenicol acetyltransferase (CAT). Transfected JB6 P+, but not P- variants, showed TPA-inducible CAT synthesis. Epidermal growth factor, another transformation promoter in JB6 cells, also caused P+ specific induction of CAT gene expression. These results demonstrate an association between induced AP-1 function and sensitivity to promotion of neoplastic transformation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bernstein, L R -- Colburn, N H -- New York, N.Y. -- Science. 1989 May 5;244(4904):566-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Johns Hopkins University, Department of Biology, Baltimore, MD 21218.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2541502" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Line ; *Cell Transformation, Neoplastic ; Chloramphenicol O-Acetyltransferase/genetics ; Cloning, Molecular ; DNA-Binding Proteins/genetics/*physiology ; Epidermal Growth Factor/pharmacology ; Epidermis ; Gene Expression Regulation ; Genetic Variation ; Kinetics ; Mice ; Nucleic Acid Hybridization ; Plasmids ; Promoter Regions, Genetic ; Proto-Oncogene Proteins ; Proto-Oncogene Proteins c-jun ; Simplexvirus/genetics ; Tetradecanoylphorbol Acetate/*pharmacology ; Transcription Factors/genetics/*physiology ; Transfection
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  • 2
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-04-28
    Description: The specific hydrolysis of unactivated esters bearing an R or S enantiomeric alcohol has been achieved by two separate classes of catalytic antibodies induced to bind either the R or S substrates. The antibodies exhibit rate accelerations (10(3) to 10(5] above background hydrolysis that, coupled with their antipodal specificity, provide a novel set of reagents for use in synthesis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Janda, K D -- Benkovic, S J -- Lerner, R A -- New York, N.Y. -- Science. 1989 Apr 28;244(4903):437-40.〈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/2717936" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Antibodies, Monoclonal/immunology ; Antibody Specificity ; Antigens/immunology ; Benzyl Alcohols/metabolism ; *Catalysis ; Esters/metabolism ; Haptens ; Hemocyanin/immunology ; Hydrolysis ; Immunization ; Kinetics ; Lipase/*metabolism ; Mice ; Mice, Inbred A ; Molecular Structure ; Organophosphonates/immunology ; Stereoisomerism ; Substrate Specificity
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  • 3
    Publication Date: 1989-03-10
    Description: Antisense RNA-mediated inhibition of gene expression was used to investigate the biological function of the c-raf-1 gene in a radiation-resistant human squamous carcinoma cell line, SQ-20B. S1 nuclease protection assays revealed that transfection of full-length raf complementary DNA in the antisense orientation (AS) leads to a specific reduction (greater than tenfold) of steady-state levels of the endogenous c-raf-1 sense (S) transcript in SQ-20B cells. In nude mice, the malignant potential of SQ-20B cells transfected with raf (S) was significantly increased relative to that of SQ-20B cells transfected with raf (AS). SQ-20B cells containing transfected raf (S) maintained a radiation-resistant phenotype as compared to those cells harboring the AS version, which appeared to have enhanced radiation sensitivity. These data indicate that the reduced expression of endogenous c-raf-1 is sufficient to modulate the tumorigenicity and the radiation-resistant phenotype of SQ-20B cells, thus implicating c-raf-1 in a pathway important to the genesis of this type of cancer.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kasid, U -- Pfeifer, A -- Brennan, T -- Beckett, M -- Weichselbaum, R R -- Dritschilo, A -- Mark, G E -- New York, N.Y. -- Science. 1989 Mar 10;243(4896):1354-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Radiation Medicine, Vincent T. Lombardi Comprehensive Cancer Research Center, Georgetown University Medical Center, Washington 20007.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2466340" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Blotting, Southern ; Carcinoma, Squamous Cell/*genetics ; Cell Line ; Cell Survival/*radiation effects ; Clone Cells ; Dose-Response Relationship, Radiation ; *Gene Expression Regulation ; Humans ; Kinetics ; Mice ; Mice, Nude ; Neoplasm Transplantation ; Nucleic Acid Hybridization ; *Proto-Oncogenes ; RNA/*genetics ; RNA, Antisense ; RNA, Messenger/*antagonists & inhibitors ; Transcription, Genetic ; Transfection ; Transplantation, Heterologous ; Tumor Cells, Cultured/*radiation effects
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  • 4
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-06-09
    Description: Two types of potassium-selective channels activated by intracellular arachidonic acid or phosphatidylcholine have been found in neonatal rat atrial cells. In inside-out patches, arachidonic acid and phosphatidylcholine each opened outwardly rectifying potassium-selective channels with conductances of 160 picosiemens (IK.AA) and 68 picosiemens (IK.PC), respectively. These potassium channels were not sensitive to internally applied adenosine triphosphate (ATP), magnesium, or calcium. Lowering the intracellular pH from 7.2 to 6.8 or 6.4 reversibly increased IK.AA channel activity three- or tenfold, respectively. A number of fatty acid derivatives were tested for their ability to activate IK.AA. These potassium-selective channels may help explain the increase in potassium conductance observed in ischemic cells and raise the possibility that fatty acid derivatives act as second messengers.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kim, D -- Clapham, D E -- HL 34873/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1989 Jun 9;244(4909):1174-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pharmacology, Mayo Foundation, Rochester, MN 55905.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2727703" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Animals, Newborn ; Arachidonic Acids/*pharmacology ; Atrial Function ; Heart/*physiology ; Hydrogen-Ion Concentration ; In Vitro Techniques ; Kinetics ; Membrane Potentials ; Phosphatidylcholines/*pharmacology ; Potassium Channels/drug effects/*physiology ; Rats
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  • 5
    Publication Date: 1989-09-15
    Description: The neutrophil Mac-1 and gp100MEL-14 adhesion proteins are involved in neutrophil extravasation during inflammation. Both the expression and activity of Mac-1 are greatly increased after neutrophil activation. In contrast, neutrophils shed gp100MEL-14 from the cell surface within 4 minutes after activation with chemotactic factors or phorbol esters, releasing a 96-kilodalton fragment of the antigen into the supernatant. Immunohistology showed that gp100MEL-14 was downregulated on neutrophils that had extravasated into inflamed tissue. The gp100MEL-14 adhesion protein may participate in the binding of unactivated neutrophils to the endothelium; rapid shedding of gp100MEL-14 may prevent extravasation into and damage of normal tissues by activated neutrophils.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kishimoto, T K -- Jutila, M A -- Berg, E L -- Butcher, E C -- AI 19957/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1989 Sep 15;245(4923):1238-41.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology, Stanford University, CA 94305.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2551036" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antigens, Differentiation/*immunology ; Antigens, Surface/*immunology ; Bone Marrow Cells ; Cell Adhesion ; Cell Adhesion Molecules ; Chemotactic Factors/*physiology ; Complement C5/physiology ; Complement C5a ; Fluorescent Antibody Technique ; Interleukin-1/physiology ; Interleukin-8 ; Kinetics ; Leukotriene B4/physiology ; Lipopolysaccharides/physiology ; Lymphocyte Activation ; Macrophage Activation ; Macrophage-1 Antigen ; Mice ; Mice, Inbred BALB C ; Neutrophils/cytology/*immunology ; Tetradecanoylphorbol Acetate ; Tumor Necrosis Factor-alpha/physiology
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  • 6
    Publication Date: 1989-04-07
    Description: Protein engineering and x-ray crystallography have been used to study the role of a surface loop that is present in pancreatic phospholipases but is absent in snake venom phospholipases. Removal of residues 62 to 66 from porcine pancreatic phospholipase A2 does not change the binding constant for micelles significantly, but it improves catalytic activity up to 16 times on micellar (zwitterionic) lecithin substrates. In contrast, the decrease in activity on negatively charged substrates is greater than fourfold. A crystallographic study of the mutant enzyme shows that the region of the deletion has a well-defined structure that differs from the structure of the wild-type enzyme. No structural changes in the active site of the enzyme were detected.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kuipers, O P -- Thunnissen, M M -- de Geus, P -- Dijkstra, B W -- Drenth, J -- Verheij, H M -- de Haas, G H -- New York, N.Y. -- Science. 1989 Apr 7;244(4900):82-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, University of Utrecht, The Netherlands.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2704992" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Crystallography ; Enzyme Activation ; Kinetics ; Molecular Sequence Data ; Mutation ; Pancreas/enzymology ; Phospholipases/*metabolism ; Phospholipases A/genetics/*metabolism/physiology ; Phospholipases A2 ; *Protein Conformation ; Snake Venoms/analysis ; Structure-Activity Relationship ; Swine
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  • 7
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-08-04
    Description: The origin of allostery is an unanswered question in the evolution of complex regulatory proteins. Anabolic ornithine transcarbamoylase, a trimer of identical subunits, is not an allosteric enzyme per se. However, when the active-site residue arginine-106 of the Escherichia coli enzyme is replaced with a glycine through site-directed mutagenesis, the resultant mutant enzyme manifests substrate cooperativity that is absent in the wild-type enzyme. Both homotropic and heterotropic interactions occur in the mutant enzyme. The initial velocity saturation curves of the substrates, carbamoyl phosphate and L-ornithine, conform to the Hill equation. The observed cooperativity depends on substrate but not enzyme concentration. The finding underscores the possibility that a single mutation of the enzyme in the cell could turn transcarbamoylation into a regulatory junction in the biosynthesis of L-arginine and urea.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kuo, L C -- Zambidis, I -- Caron, C -- DK01721/DK/NIDDK NIH HHS/ -- DK38089/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1989 Aug 4;245(4917):522-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Metcalf Center for Science and Engineering, Boston University, MA 02215.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2667139" target="_blank"〉PubMed〈/a〉
    Keywords: Allosteric Regulation ; Binding Sites ; Carbamyl Phosphate/metabolism ; Escherichia coli/*enzymology ; Glycine ; Kinetics ; Macromolecular Substances ; *Mutation ; Ornithine/metabolism ; Ornithine Carbamoyltransferase/*genetics/metabolism ; Structure-Activity Relationship ; Zinc/pharmacology
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  • 8
    Publication Date: 1989-07-07
    Description: Basic fibroblast growth factor (bFGF) participates in many processes including early developmental events, angiogenesis, wound healing, and maintenance of neuronal cell viability. A 130-kilodalton protein was isolated on the basis of its ability to specifically bind to bFGF. A complementary DNA clone was isolated with an oligonucleotide probe corresponding to determined amino acid sequences of tryptic peptide fragments of the purified protein. The putative bFGF receptor encoded by this complementary DNA is a transmembrane protein that contains three extracellular immunoglobulin-like domains, an unusual acidic region, and an intracellular tyrosine kinase domain. These domains are arranged in a pattern that is different from that of any growth factor receptor described.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lee, P L -- Johnson, D E -- Cousens, L S -- Fried, V A -- Williams, L T -- CA 21765/CA/NCI NIH HHS/ -- R01 HL32898/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1989 Jul 7;245(4913):57-60.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Medicine, University of California, San Francisco 94143.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2544996" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Base Sequence ; Cells, Cultured ; Chick Embryo ; *Cloning, Molecular ; DNA/*genetics ; Fibroblast Growth Factors/*genetics ; Kinetics ; Mice ; Molecular Sequence Data ; Peptide Fragments/analysis ; Receptors, Cell Surface/*genetics/metabolism ; Receptors, Fibroblast Growth Factor ; Recombinant Proteins/metabolism
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  • 9
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-11-17
    Description: Rana esculenta tropomyosin assembles in vivo into a coiled-coil alpha helix from two different subunits, alpha and beta, which are present in about equal concentrations. Although the native composition is alpha beta, a mixture of equal amounts of alpha alpha and beta beta is produced by refolding dissociated alpha and beta at low temperature in vitro. Refolding kinetics showed that alpha alpha formed first and was relatively stable with regard to chain exchange below approximately 20 degrees C. Equilibration of the homodimer mixture at 30 degrees and 34 degrees C for long times, however, resulted in the formation of the native alpha beta molecule by chain exchange. Biosynthesis of alpha beta from separate alpha and beta genes is, therefore, favored thermodynamically over the formation of homodimers, and biological factors need not be invoked to explain the preferred native alpha beta composition.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lehrer, S S -- Qian, Y D -- Hvidt, S -- HL22461/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1989 Nov 17;246(4932):926-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Muscle Research, Boston Biomedical Research Institute, MA 02114.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2814515" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Kinetics ; Macromolecular Substances ; Muscle, Smooth/metabolism ; Muscles/metabolism ; Myocardium/metabolism ; Protein Conformation ; Protein Denaturation ; Protein Processing, Post-Translational ; Rana esculenta ; Thermodynamics ; Tropomyosin/genetics/*metabolism
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  • 10
    Publication Date: 1989-01-13
    Description: An important question in protein folding is whether the natural amino and carboxyl termini and the given order of secondary structure segments are critical to the stability and to the folding pathway of proteins. Here it is shown that two circularly permuted versions of the gene of a single-domain beta alpha barrel enzyme can be expressed in Escherichia coli. The variants are enzymically active and are practically indistinguishable from the original enzyme by several structural and spectroscopic criteria, despite the creation of new termini and the cleavage of a surface loop. This novel genetic approach should be useful for protein folding studies both in vitro and in vivo.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Luger, K -- Hommel, U -- Herold, M -- Hofsteenge, J -- Kirschner, K -- New York, N.Y. -- Science. 1989 Jan 13;243(4888):206-10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Abteilung Biophysikalische Chemie, Universitat Basel, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2643160" target="_blank"〉PubMed〈/a〉
    Keywords: *Aldose-Ketose Isomerases ; Amino Acid Sequence ; Base Sequence ; Carbohydrate Epimerases/*genetics/metabolism ; Circular Dichroism ; *Cloning, Molecular ; Enzyme Stability ; Escherichia coli/*enzymology/genetics ; *Genes ; Genetic Variation ; Kinetics ; Molecular Sequence Data ; *Protein Conformation ; Spectrometry, Fluorescence ; Spectrophotometry, Ultraviolet
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  • 11
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-11-03
    Description: An important control point in gene expression is at the level of messenger RNA (mRNA) stability. The mRNAs of certain regulatory cellular proteins such as oncogenes, cytokines, lymphokines, and transcriptional activators are extremely labile. These messages share a common AUUUA pentamer in their 3' untranslated region, which confers cytoplasmic instability. A cytosolic protein was identified that binds specifically to RNA molecules containing four reiterations of the AUUUA structural element. This protein consists of three subunits and binds rapidly to AUUUA-containing RNA. Such protein-RNA complexes are resistant to the actions of denaturing and reducing agents, demonstrating very stable binding. The time course, stability, and specificity of the protein-AUUUA interaction suggests the possibility that the formation of this complex may target susceptible mRNA for rapid cytoplasmic degradation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Malter, J S -- CA01427-01/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1989 Nov 3;246(4930):664-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology, Tulane University School of Medicine, New Orleans, LA 70112.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2814487" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Binding, Competitive ; Carrier Proteins/isolation & purification/*metabolism ; Cell Line ; Humans ; Kinetics ; Macromolecular Substances ; Molecular Weight ; *Nucleocytoplasmic Transport Proteins ; RNA, Messenger/*metabolism ; *RNA-Binding Proteins ; Ribonuclease, Pancreatic
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  • 12
    Publication Date: 1989-06-09
    Description: Arachidonic acid, as well as fatty acids that are not substrates for cyclooxygenase and lipoxygenase enzymes, activated a specific type of potassium channel in freshly dissociated smooth muscle cells. Activation occurred in excised membrane patches in the absence of calcium and all nucleotides. Therefore signal transduction pathways that require such soluble factors, including the NADPH-dependent cytochrome P450 pathway, do not mediate the response. Thus, fatty acids directly activate potassium channels and so may constitute a class of signal molecules that regulate ion channels.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ordway, R W -- Walsh, J V Jr -- Singer, J J -- DK-31620/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1989 Jun 9;244(4909):1176-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology, University of Massachusetts Medical School, Worcester 01655.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2471269" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Arachidonic Acid ; Arachidonic Acids/*pharmacology ; Bufo marinus ; Fatty Acids, Nonesterified/*pharmacology ; In Vitro Techniques ; Ion Channels/drug effects/*physiology ; Kinetics ; Membrane Potentials/drug effects ; Muscle, Smooth/*physiology ; Stomach/physiology
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  • 13
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-12-22
    Description: The contribution of the anticodon to the discrimination between cognate and noncognate tRNAs by Escherichia coli Arg-tRNA synthetase has been investigated by in vitro synthesis and aminoacylation of elongator methionine tRNA (tRNA(mMet) mutants. Substitution of the Arg anticodon CCG for the Met anticodon CAU leads to a dramatic increase in Arg acceptance by tRNA(mMet). A nucleotide (A20) previously identified by others in the dihydrouridine loop of tRNA(Arg)s makes a smaller contribution to the conversion of tRNA(mMet) identity from Met to Arg. The combined anticodon and dihydrouridine loop mutations yield a tRNA(mMet) derivative that is aminoacylated with near-normal kinetics by the Arg-tRNA synthetase.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schulman, L H -- Pelka, H -- New York, N.Y. -- Science. 1989 Dec 22;246(4937):1595-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Developmental Biology and Cancer, Albert Einstein College of Medicine, Bronx, NY 10461.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2688091" target="_blank"〉PubMed〈/a〉
    Keywords: Anticodon/*genetics ; Arginine-tRNA Ligase/metabolism ; Base Sequence ; Escherichia coli/enzymology/genetics ; Kinetics ; Methionine-tRNA Ligase/metabolism ; Molecular Sequence Data ; Nucleic Acid Conformation ; RNA, Transfer/*genetics ; RNA, Transfer, Amino Acid-Specific/*genetics ; RNA, Transfer, Arg/*genetics ; Substrate Specificity ; T-Phages/genetics ; Transcription, Genetic
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  • 14
    Publication Date: 1989-06-09
    Description: Vasoactive intestinal peptide (VIP) labeled with 125I, [Tyr10-125I]VIP, can be hydrolyzed by immunoglobulin G (IgG) purified from a human subject, as judged by trichloroacetic acid precipitation and reversed-phase high-performance liquid chromatography (HPLC). The hydrolytic activity was precipitated by antibody to human IgG, it was bound by immobilized protein G and showed a molecular mass close to 150 kilodaltons by gel filtration chromatography, properties similar to those of authentic IgG. The Fab fragment, prepared from IgG by papain treatment, retained the VIP hydrolytic activity of the IgG. Peptide fragments produced by treatment of VIP with the antibody fraction were purified by reversed-phase HPLC and identified by fast atom bombardment-mass spectrometry and peptide sequencing. The scissile bond in VIP deduced from these experiments was Gln16-Met17. The antibody concentration (73.4 fmol per milligram of IgG) and the Kd (0.4 nM) were computed from analysis of VIP binding under conditions that did not result in peptide hydrolysis. Analysis of the antibody-mediated VIP hydrolysis at varying concentrations of substrate suggested conformity with Michaelis-Menton kinetics (Km). The values for Km (37.9 X 10(-9) M) and the turnover number kcat (15.6 min-1) suggested relatively tight VIP binding and a moderate catalytic efficiency of the antibody.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Paul, S -- Volle, D J -- Beach, C M -- Johnson, D R -- Powell, M J -- Massey, R J -- HL 35506/HL/NHLBI NIH HHS/ -- HL 40348/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1989 Jun 9;244(4909):1158-62.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pharmacology, University of Nebraska Medical Center, Omaha 68105.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2727702" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; *Autoantibodies ; Catalysis ; Chromatography, High Pressure Liquid ; Humans ; Hydrolysis ; Immunoglobulin Fab Fragments ; *Immunoglobulin G ; Kinetics ; Molecular Sequence Data ; Peptide Fragments/isolation & purification ; Vasoactive Intestinal Peptide/*immunology
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  • 15
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-11-17
    Description: A phosphonate monoester, m-carboxyphenyl phenylacetamidomethylphosphonate, has been found to be a specific inhibitor of the class C beta-lactamase of Enterobacter cloacae P99. Inactivation is rapid (10(3) per second per molar concentration) and reactivation very slow (2.2 X 10(-6) per second). Apparently concerted with the inactivation, one equivalent (with respect to the enzyme) of m-hydroxybenzoate is released. Reactivation is accelerated by hydroxylamine and benzohydroxamate. This suggests that the loss of enzyme activity is due to phosphonylation of an active site functional group. This discovery holds the promise of a new general class of beta-lactamase inhibitors and, perhaps, antibiotics.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pratt, R F -- New York, N.Y. -- Science. 1989 Nov 17;246(4932):917-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Chemistry Department, Wesleyan University, Middletown, CT 06457.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2814513" target="_blank"〉PubMed〈/a〉
    Keywords: Enterobacter/*enzymology ; Enterobacteriaceae/*enzymology ; Hydroxamic Acids/pharmacology ; Hydroxylamine ; Hydroxylamines/pharmacology ; Kinetics ; Organophosphorus Compounds/*pharmacology ; Protein Binding ; *beta-Lactamase Inhibitors
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  • 16
    Publication Date: 1989-04-28
    Description: The rapid transductional sequences initiated by interferon-gamma (IFN-gamma) on binding to its receptor regulate functional and genomic responses in many cells but are not well defined. Induction of macrophage activation is an example of such functional and genomic changes in response to IFN-gamma. Addition of IFN-gamma to murine macrophages, at activating concentrations, produced rapid (within 60 seconds) alkalinization of the cytosol and a concomitant, rapid influx of 22Na+. Amiloride inhibited the ion fluxes and the accumulation of specific messenger RNA for two genes induced by IFN-gamma (the early gene JE and the beta chain of the class II major histocompatibility complex gene I-A). The data indicate that IFN-gamma initiates rapid exchange of Na+ and H+ by means of the Na+/H+ antiporter and that these amiloride-sensitive ion fluxes are important to some of the genomic effects of IFN-gamma.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Prpic, V -- Yu, S F -- Figueiredo, F -- Hollenbach, P W -- Gawdi, G -- Herman, B -- Uhing, R J -- Adams, D O -- New York, N.Y. -- Science. 1989 Apr 28;244(4903):469-71.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology, Duke University Medical Center, Durham, NC 27710.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2541500" target="_blank"〉PubMed〈/a〉
    Keywords: Amiloride/pharmacology ; Animals ; Carrier Proteins/antagonists & inhibitors/metabolism ; Cells, Cultured ; Cytosol/metabolism ; *Gene Expression Regulation ; Histocompatibility Antigens Class II/*genetics ; Hydrogen-Ion Concentration ; Interferon-gamma/*physiology ; Kinetics ; Macrophage Activation ; Macrophages/drug effects/metabolism ; Mice ; *Protons ; RNA, Messenger/biosynthesis ; Sodium/*metabolism ; Sodium-Hydrogen Antiporter
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  • 17
    Publication Date: 1989-08-11
    Description: The endogenous c-mos product, pp39mos, is required for progesterone-induced meiotic maturation in Xenopus oocytes. Treatment of oocytes with progesterone induced a rapid increase in pp39mos that preceded both the activation of maturation promoting factor (MPF) and germinal vesicle breakdown (GVBD). Microinjection of synthetic mos RNA into oocytes activated MPF and induced GVBD in the absence of progesterone. Thus, the mos proto-oncogene product may qualify as a candidate "initiator" protein of MPF and is at least one of the "triggers" for G2 to M transition.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sagata, N -- Daar, I -- Oskarsson, M -- Showalter, S D -- Vande Woude, G F -- N01-CO-74101/CO/NCI NIH HHS/ -- New York, N.Y. -- Science. 1989 Aug 11;245(4918):643-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉BRI-Basic Research Program, National Cancer Institute, Frederick Cancer Research Facility, MD 21701.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2474853" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Cycloheximide/pharmacology ; Female ; Growth Substances/physiology ; Kinetics ; Maturation-Promoting Factor ; Meiosis/drug effects ; Microinjections ; Oocytes/*physiology ; Progesterone/pharmacology ; Protein Biosynthesis ; Proto-Oncogene Proteins/genetics/*physiology ; Proto-Oncogene Proteins c-mos ; RNA/genetics ; Transcription, Genetic ; Transfection ; Xenopus
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  • 18
    Publication Date: 1989-02-17
    Description: Salmonella bacteria are capable of entering (invading) and multiplying within eukaryotic cells. Stable adherence to and invasion of epithelial cells by S. choleraesuis and S. typhimurium were found to require de novo synthesis of several new bacterial proteins. This inducible event appears to be a coordinately regulated system dependent on trypsin- and neuraminidase-sensitive structures present on the epithelial cell surface. Mutants of S. choleraesuis and S. typhimurium were unable to synthesize these proteins and did not stably adhere to nor invade eukaryotic cells. Two such S. typhimurium mutants were avirulent in mice, an indication that these proteins are required for Salmonella virulence.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Finlay, B B -- Heffron, F -- Falkow, S -- AI26195/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1989 Feb 17;243(4893):940-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Medical Microbiology, Stanford University School of Medicine, CA 94305.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2919285" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Bacterial Adhesion ; Bacterial Proteins/*biosynthesis ; Cell Line ; Epithelium/physiology ; Kinetics ; Methionine/metabolism ; Salmonella/pathogenicity/*physiology ; Sulfur Radioisotopes
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  • 19
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-12-22
    Description: Analysis of crosslinked complexes of M1 RNA, the catalytic RNA subunit of ribonuclease P from Escherichia coli, and transfer RNA precursor substrates has led to the identification of regions in the enzyme and in the substrate that are in close physical proximity to each other. The nucleotide in M1 RNA, residue C92, which participates in a crosslink with the substrate was deleted and the resulting mutant M1 RNA was shown to cleave substrates lacking the 3' terminal CCAUCA sequence at sites several nucleotides away from the normal site of cleavage. The presence or absence of the 3' terminal CCAUCA sequence in transfer RNA precursor substrates markedly affects the way in which these substrates interact with the catalytic RNA in the enzyme-substrate complex. The contacts between wild-type M1 RNA and its substrate are in a region that resembles part of the transfer RNA "E" (exit) site in 23S ribosomal RNA. These data demonstrate that in RNA's with very different cellular functions, there are domains with similar structural and functional properties and that there is a nucleotide in M1 RNA that affects the site of cleavage by the enzyme.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Guerrier-Takada, C -- Lumelsky, N -- Altman, S -- New York, N.Y. -- Science. 1989 Dec 22;246(4937):1578-84.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Yale University, New Haven, CT 06520.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2480641" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Endoribonucleases/genetics/*metabolism ; Escherichia coli/enzymology/*genetics ; *Escherichia coli Proteins ; Kinetics ; Molecular Sequence Data ; Nucleic Acid Conformation ; RNA Precursors/genetics ; RNA, Bacterial/*genetics/metabolism ; RNA, Transfer/genetics ; Ribonuclease P ; Substrate Specificity
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  • 20
    Publication Date: 1989-05-12
    Description: The intervening sequence of the ribosomal RNA precursor of Tetrahymena is a catalytic RNA molecule, or ribozyme. Acting as a sequence-specific endoribonuclease, it cleaves single-stranded RNA substrates with concomitant addition of guanosine. The chemistry of the reaction has now been studied by introduction of a single phosphorothioate in the substrate RNA at the cleavage site. Kinetic studies show no significant effect of this substitution on kcat (rate constant) or Km (Michaelis constant), providing evidence that some step other than the chemical step is rate-limiting. Product analysis reveals that the reaction proceeds with inversion of configuration at phosphorus, consistent with an in-line, SN2 (P) mechanism. Thus, the ribozyme reaction is in the same mechanistic category as the individual displacement reactions catalyzed by protein nucleotidyltransferases, phosphotransferases, and nucleases.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉McSwiggen, J A -- Cech, T R -- GM28039/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1989 May 12;244(4905):679-83.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309-0215.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2470150" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Guanosine/metabolism ; Hydrolysis ; Kinetics ; Molecular Conformation ; Phosphates/metabolism ; Phosphorus ; RNA/*metabolism ; RNA Precursors/*metabolism ; RNA Splicing ; RNA, Catalytic ; RNA, Ribosomal/*metabolism ; Tetrahymena/*genetics ; Thionucleotides/metabolism
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  • 21
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-06-02
    Description: Double-stranded (ds) RNA and many viruses are inducers of interferon (IFN), the latter presumably because they contain, or can form, dsRNA. Concomitant with the induction of IFN in chicken embryo cells was the induction of a novel double-stranded ribonuclease (dsRNase), which was released into the medium and continued to accumulate long after IFN production ceased. Only avian cells (chicken, quail, turkey, or duck) expressed high levels of this dsRNase; mammalian, turtle, or fish cells did not. Production of the nuclease was inducer dose-dependent. Optimum pH and cation requirements distinguished it from other dsRNase activities. Degradation of dsRNA was endonucleolytic. Activity resided in a molecule of an Mr of approximately 34,500. Low levels of a single-stranded (ss) RNase activity were inseparable from the dsRNase. The role for a dsRNA-inducible dsRNase released from cells is unknown.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Meegan, J M -- Marcus, P I -- AI18381/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1989 Jun 2;244(4908):1089-91.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular and Cell Biology, The University of Connecticut, Storrs 06269.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2471268" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Birds/embryology/*metabolism ; Cations ; Chick Embryo ; Ducks/embryology ; Endoribonucleases/*biosynthesis ; Enzyme Induction ; Hydrogen-Ion Concentration ; Interferon Inducers/pharmacology ; Interferons/*metabolism ; Kinetics ; Newcastle disease virus/physiology/radiation effects ; Poly I-C/pharmacology ; Quail/embryology ; RNA, Double-Stranded/metabolism ; Species Specificity ; Substrate Specificity ; Turkeys/embryology ; Ultraviolet Rays
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  • 22
    Publication Date: 1989-05-12
    Description: Methotrexate coupled to maleylated bovine serum albumin was taken up efficiently through the "scavenger" receptors present on macrophages and led to selective killing of intracellular Leishmania mexicana amazonensis amastigotes in cultured hamster peritoneal macrophages. The drug conjugate was nearly 100 times as effective as free methotrexate in eliminating the intracellular parasites. Furthermore, in a model of experimental cutaneous leishmaniasis in hamsters, the drug conjugate brought about more than 90% reduction in the size of footpad lesions within 11 days. In contrast, the free drug at a similar concentration did not significantly affect lesion size. These studies demonstrate the potential of receptor-mediated drug delivery in the therapy of macrophage-associated diseases.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mukhopadhyay, A -- Chaudhuri, G -- Arora, S K -- Sehgal, S -- Basu, S K -- New York, N.Y. -- Science. 1989 May 12;244(4905):705-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Microbial Technology, Chandigarh, India.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2717947" target="_blank"〉PubMed〈/a〉
    Keywords: Albumins/*administration & dosage/metabolism ; Animals ; Cells, Cultured ; Cricetinae ; Female ; Kinetics ; Leishmania mexicana/*drug effects ; Leishmaniasis/*drug therapy ; Macrophages/metabolism/*parasitology ; Male ; *Membrane Proteins ; Mesocricetus ; Methotrexate/*administration & dosage/pharmacology/therapeutic use ; *Receptors, Immunologic/metabolism ; *Receptors, Lipoprotein ; Receptors, Scavenger ; Scavenger Receptors, Class B ; Serum Albumin, Bovine
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  • 23
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-12-22
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schwarz, S -- Pohl, P -- Zhou, G Z -- New York, N.Y. -- Science. 1989 Dec 22;246(4937):1635-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2556797" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Binding, Competitive ; Brain/metabolism ; Kinetics ; Ligands ; Lymphocytes/metabolism ; Progesterone/blood/cerebrospinal fluid/metabolism ; Receptors, Opioid/*metabolism ; Receptors, sigma ; Steroids/*metabolism/pharmacology
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  • 24
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-10-06
    Description: A microscopic method for simulating quantum mechanical, nuclear tunneling effects in biological electron transfer reactions is presented and applied to several electron transfer steps in photosynthetic bacterial reaction centers. In this "dispersed polaron" method the fluctuations of the protein and the electron carriers are projected as effective normal modes onto an appropriate reaction coordinate and used to evaluate the quantum mechanical rate constant. The simulations, based on the crystallographic structure of the reaction center from Rhodopseudomonas viridis, focus on electron transfer from a bacteriopheophytin to a quinone and the subsequent back-reaction. The rates of both of these reactions are almost independent of temperature or even increase with decreasing temperature. The simulations reproduce this unusual temperature dependence in a qualitative way, without the use of adjustable parameters for the protein's Franck-Condon factors. The observed dependence of the back-reaction on the free energy of the reaction also is reproduced, including the special behavior in the "inverted region."〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Warshel, A -- Chu, Z T -- Parson, W W -- GM-40283/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1989 Oct 6;246(4926):112-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of Southern California, Los Angeles 90007.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2675313" target="_blank"〉PubMed〈/a〉
    Keywords: Bacterial Proteins/*metabolism ; *Electron Transport ; Kinetics ; Models, Chemical ; *Photosynthesis ; Photosynthetic Reaction Center Complex Proteins ; Rhodopseudomonas/metabolism ; Thermodynamics
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  • 25
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-03-17
    Description: A true Bronsted analysis of proton transfer in an enzyme mechanism is made possible by the chemical rescue of an inactive mutant of aspartate aminotransferase, where the endogenous general base, Lys258, is replaced with Ala by site-directed mutagenesis. Catalytic activity is restored to this inactive mutant by exogenous amines. The eleven amines studied generate a Bronsted correlation with beta of 0.4 for the transamination of cysteine sulfinate, when steric effects are included in the regression analysis. Localized mutagenesis thus allows the classical Bronsted analysis of transition-state structure to be applied to enzyme-catalyzed reactions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Toney, M D -- Kirsch, J F -- GM07232/GM/NIGMS NIH HHS/ -- GM35393/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1989 Mar 17;243(4897):1485-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, University of California, Berkeley 94720.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2538921" target="_blank"〉PubMed〈/a〉
    Keywords: Amines ; Aspartate Aminotransferases/*metabolism ; Binding Sites ; Catalysis ; Escherichia coli/enzymology ; Kinetics ; Lysine ; Mutation ; Protons
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  • 26
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-02-24
    Description: Gadolinium ions produce three distinct kinds of block of the stretch-activated (SA) ion channels in Xenopus oocytes: a concentration-dependent reduction in channel open time, a concentration-dependent reduction in open channel current, and a unique, steeply concentration-dependent, reversible inhibition of channel opening. This last effect reduces the probability of a channel being open from about 10(-1) at 5 microM to less than 10(-5) at 10 microM gadolinium. Calcium has effects on open time and current similar to that of gadolinium, but this channel is permeable to calcium and calcium does not completely inhibit channel activity. The availability of a blocker for SA ion channels may help to define their physiological function, and will simplify the use of oocytes as an expression system for ion channels.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yang, X C -- Sachs, F -- DK-37792/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1989 Feb 24;243(4894 Pt 1):1068-71.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉State University of New York, Buffalo 14214.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2466333" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Binding, Competitive ; Calcium/*pharmacology ; Cations ; Electric Conductivity ; Female ; Gadolinium/*pharmacology ; Ion Channels/drug effects/*physiology ; Kinetics ; Oocytes/*physiology ; Xenopus
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  • 27
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-07-07
    Description: beta-Adrenergic agonists activate the G protein, Gs, which stimulates cardiac calcium currents by both cytoplasmic, indirect and membrane-delimited, direct pathways. To test whether beta-adrenergic agonists might use both pathways in the heart, isoproterenol was rapidly applied to cardiac myocytes, resulting in a biphasic increase in cardiac calcium channel currents that had time constants of 150 milliseconds and 36 seconds. beta-Adrenergic antagonists of a G protein inhibitor blocked both the fast and slow responses, whereas the adenylyl cyclase activator forskolin produced only the slow response. The presence of a fast pathway in the heart can explain what the slow pathway cannot account for: the ability of cardiac sympathetic nerves to change heart rate within a single beat.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yatani, A -- Brown, A M -- HL36930/HL/NHLBI NIH HHS/ -- HL37044/HL/NHLBI NIH HHS/ -- NS23877/NS/NINDS NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1989 Jul 7;245(4913):71-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2544999" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Atrial Function ; Calcium Channels/drug effects/*physiology ; Carbachol/pharmacology ; Cells, Cultured ; Colforsin/pharmacology ; GTP-Binding Proteins/*physiology ; Guinea Pigs ; Heart/*physiology ; Isoproterenol/*pharmacology ; Kinetics ; Membrane Potentials/drug effects ; *Signal Transduction
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  • 28
    Publication Date: 1989-11-03
    Description: Many Gram-negative bacteria export proteins to the exterior. Some of these proteins are first secreted into the periplasm and then cross the outer membrane in a separate step. The source of energy required for the translocation is unknown. Export of the extracellular protein proaerolysin from the periplasm through the outer membrane of Aeromonas salmonicida is inhibited by a proton ionophore and by low extracellular pH. One possible explanation of these results is that a proton gradient across the outer membrane is required for export.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wong, K R -- Buckley, J T -- New York, N.Y. -- Science. 1989 Nov 3;246(4930):654-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Microbiology, University of Victoria, BC, Canada.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2814486" target="_blank"〉PubMed〈/a〉
    Keywords: Aeromonas/drug effects/*metabolism ; Bacterial Toxins/*metabolism ; Carbonyl Cyanide m-Chlorophenyl Hydrazone/pharmacology ; Cell Membrane/metabolism ; Culture Media ; Hemolysin Proteins/*metabolism ; Hydrogen-Ion Concentration ; Kinetics ; Pore Forming Cytotoxic Proteins
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  • 29
    Publication Date: 1989-05-26
    Description: The eye needs to biosynthesize 11-cis-retinoids because the chromophore of rhodopsin is 11-cis-retinal. The critical metabolic step is the endergonic isomerization of free all-trans-retinol (vitamin A) into 11-cis-retinol. This isomerization process can take place in isolated membranes from the retinal pigment epithelium in the absence of added energy sources. Specific binding proteins probably do not serve as an energy source, and since all of the reactions in the visual cycle are shown here to be reversible, trapping reactions also do not participate in the isomerization reaction. One previously unexplored possibility is that the chemical energy in the bonds of the membrane itself may drive the isomerization reaction. A group transfer reaction is proposed that forms a retinyl ester from a lipid acyl donor and vitamin A. This transfer can drive the isomerization reaction because the all-trans-retinyl ester is isomerized directly to 11-cis-retinol. Thus, the free energy of hydrolysis of the ester is coupled to the thermodynamically uphill trans to cis isomerization. The prediction of an obligate C-O bond cleavage in the vitamin A moiety during isomerization is borne out. Although the natural substrate for isomerization is not known, all-trans-retinyl palmitate is processed in vitro to 11-cis-retinol by pigment epithelial membranes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Deigner, P S -- Law, W C -- Canada, F J -- Rando, R R -- EY04096/EY/NEI NIH HHS/ -- New York, N.Y. -- Science. 1989 May 26;244(4907):968-71.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2727688" target="_blank"〉PubMed〈/a〉
    Keywords: Amphibians ; Animals ; Cattle ; Cell Membrane/*metabolism ; *Energy Metabolism ; Isomerases/metabolism ; Isomerism ; Kinetics ; Molecular Structure ; Pigment Epithelium of Eye/*metabolism/radiation effects ; Ultraviolet Rays ; Vitamin A/analogs & derivatives/*metabolism ; *cis-trans-Isomerases
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  • 30
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-01-13
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Catterall, W A -- New York, N.Y. -- Science. 1989 Jan 13;243(4888):236-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2536189" target="_blank"〉PubMed〈/a〉
    Keywords: Kinetics ; Ligands ; Receptors, Adrenergic, alpha/*metabolism ; Receptors, Adrenergic, beta/*metabolism ; Thermodynamics
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  • 31
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-03-10
    Description: Primary and secondary protium-to-tritium (H/T) and deuterium-to-tritium (D/T) kinetic isotope effects for the catalytic oxidation of benzyl alcohol to benzaldehyde by yeast alcohol dehydrogenase (YADH) at 25 degrees Celsius have been determined. Previous studies showed that this reaction is nearly or fully rate limited by the hydrogen-transfer step. Semiclassical mass considerations that do not include tunneling effects would predict that kH/kT = (kD/kT)3.26, where kH, kD, and kT are the rate constants for the reaction of protium, deuterium, and tritium derivatives, respectively. Significant deviations from this relation have now been observed for both primary and especially secondary effects, such that experimental H/T ratios are much greater than those calculated from the above expression. These deviations also hold in the temperature range from 0 to 40 degrees Celsius. Such deviations were previously predicted to result from a reaction coordinate containing a significant contribution from hydrogen tunneling.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cha, Y -- Murray, C J -- Klinman, J P -- New York, N.Y. -- Science. 1989 Mar 10;243(4896):1325-30.〈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/2646716" target="_blank"〉PubMed〈/a〉
    Keywords: Alcohol Dehydrogenase/*metabolism ; Benzyl Alcohols ; *Hydrogen ; Kinetics ; Mathematics ; Models, Theoretical ; Oxidation-Reduction ; Saccharomyces cerevisiae/enzymology ; Thermodynamics ; Tritium
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  • 32
    Publication Date: 1989-09-01
    Description: Human alpha- and beta-globin genes were separately fused downstream of two erythroid-specific deoxyribonuclease (DNase) I super-hypersensitive sites that are normally located 50 kilobases upstream of the human beta-globin gene. These two constructs were coinjected into fertilized mouse eggs, and expression was analyzed in transgenic animals that developed. Mice that had intact copies of the transgenes expressed high levels of correctly initiated human alpha- and beta-globin messenger RNA specifically in erythroid tissue. An authentic human hemoglobin was formed in adult erythrocytes that when purified had an oxygen equilibrium curve identical to the curve of native human hemoglobin A (Hb A). Thus, functional human hemoglobin can be synthesized in transgenic mice. This provides a foundation for production of mouse models of human hemoglobinopathies such as sickle cell disease.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Behringer, R R -- Ryan, T M -- Reilly, M P -- Asakura, T -- Palmiter, R D -- Brinster, R L -- Townes, T M -- HD-09172/HD/NICHD NIH HHS/ -- HL-35559/HL/NHLBI NIH HHS/ -- HL-38632/HL/NHLBI NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1989 Sep 1;245(4921):971-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Reproductive Physiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia 19104.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2772649" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Deoxyribonuclease I ; Female ; *Genes ; Globins/biosynthesis/*genetics ; Hemoglobins/biosynthesis/*genetics ; Humans ; Kinetics ; Mice ; Mice, Transgenic ; Oxyhemoglobins/metabolism ; RNA, Messenger/genetics ; Transcription, Genetic
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  • 33
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-06-30
    Description: High-resolution differential interference contrast microscopy and digital imaging of the fluorescent calcium indicator dye fura-2 were performed simultaneously in single rat salivary gland acinar cells to examine the effects of muscarinic stimulation on cell volume and cytoplasmic calcium concentration ([Ca2+]i). Agonist stimulation of fluid secretion is initially associated with a rapid tenfold increase in [Ca2+]i as well as a substantial cell shrinkage. Subsequent changes of cell volume in the continued presence of agonist are tightly coupled to dynamic levels of [Ca2+]i, even during [Ca2+]i oscillations. Experiments with Ca2+ chelators and ionophores showed that physiological elevations of [Ca2+]i are necessary and sufficient to cause changes in cell volume. The relation between [Ca2+]i and cell volume suggests that the latter reflects the secretory state of the acinar cell. Agonist-induced changes in [Ca2+]i, by modulating specific ion permeabilities, result in solute movement into or out of the cell. The resultant cell volume changes may be important in modulating salivary secretion.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Foskett, J K -- Melvin, J E -- New York, N.Y. -- Science. 1989 Jun 30;244(4912):1582-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Physiology Department, Armed Forces Radiobiology Research Institute, Bethesda, MD 20814.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2500708" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Benzofurans ; Calcium/*metabolism ; Carbachol/pharmacology ; Cell Membrane/physiology ; Chelating Agents ; Chlorides/metabolism ; Cytoplasm/metabolism ; Egtazic Acid/analogs & derivatives ; Ethers/pharmacology ; Fluorescent Dyes ; Fura-2 ; Ionomycin ; Ionophores ; Kinetics ; Potassium/metabolism ; Rats ; Saliva/*secretion ; Salivary Glands/*cytology/drug effects/physiology
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  • 34
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-11-25
    Description: The human immunodeficiency virus type 1 (HIV-1) shows extensive genetic variation and undergoes rapid evolution. The fidelity of purified HIV-1 reverse transcriptase was measured during DNA polymerization in vitro by means of three different assays. Reverse transcriptase from HIV-1 introduced base-substitution errors in DNA from the bacteriophage phi X174 amber3 at estimated frequencies of 1/2000 to 1/4000. Analyses of misincorporation rates opposite a single template adenine residue showed that HIV-1 reverse transcriptase catalyzed nucleotide mismatches with a specificity of A:C much greater than A:G greater than A:A. The high error rate of HIV-1 reverse transcriptase in vitro translates to approximately five to ten errors per HIV-1 genome per round of replication in vivo. This high error rate suggests that misincorporation by HIV-1 reverse transcriptase is, at least in part, responsible for the hypermutability of the AIDS virus. The specificity of misincorporation may provide a basis for the systematic construction of antiviral nucleosides.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Preston, B D -- Poiesz, B J -- Loeb, L A -- CA-07263-03/CA/NCI NIH HHS/ -- N01AI72654/AI/NIAID NIH HHS/ -- R35-CA-39903/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1988 Nov 25;242(4882):1168-71.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology, University of Washington, Seattle 98195.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2460924" target="_blank"〉PubMed〈/a〉
    Keywords: Avian Myeloblastosis Virus/enzymology ; Bacteriophage phi X 174/genetics ; DNA/*biosynthesis ; DNA Polymerase II/metabolism ; DNA, Viral/biosynthesis ; Electrophoresis, Polyacrylamide Gel ; HIV/*enzymology/genetics ; Kinetics ; Moloney murine leukemia virus/enzymology ; Mutation ; Nucleotides/metabolism ; RNA-Directed DNA Polymerase/*metabolism
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  • 35
    Publication Date: 1988-04-22
    Description: BC3H1 myocytes release membrane-bound alkaline phosphatase to the incubation medium upon stimulation with insulin, following a time course that is consistent with the generation of dimyristoylglycerol and the appearance of a putative insulin mediator in the extracellular medium. The use of specific blocking agents shows, however, that alkaline phosphatase release and dimyristoylglycerol production are independent processes and that the blockade of either event inhibits the production of insulin mediator. These experiments suggest a new model of insulin action.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Romero, G -- Luttrell, L -- Rogol, A -- Zeller, K -- Hewlett, E -- Larner, J -- AI 18000/AI/NIAID NIH HHS/ -- AM 14334/AM/NIADDK NIH HHS/ -- AM 22125/AM/NIADDK NIH HHS/ -- New York, N.Y. -- Science. 1988 Apr 22;240(4851):509-11.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pharmacology, University of Virginia School of Medicine, Charlottesville 22908.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3282305" target="_blank"〉PubMed〈/a〉
    Keywords: Alkaline Phosphatase/metabolism/secretion ; Animals ; Diglycerides/metabolism ; Enzyme Activation/drug effects ; Extracellular Space/enzymology ; Glycolipids/*physiology ; In Vitro Techniques ; Insulin/*pharmacology ; Kinetics ; Membrane Glycoproteins/*physiology ; Phosphatidylinositols/*physiology ; Pyruvate Dehydrogenase Complex/metabolism
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  • 36
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-11-04
    Description: The anticodon has previously been shown to play a role in recognition of certain transfer RNAs by aminoacyl-tRNA synthetases; however, the extent to which this sequence dictates tRNA identity is generally unknown. To investigate the contribution of the anticodon to the identity of Escherichia coli methionine and valine tRNAs, in vitro transcripts of these tRNAs were prepared that contained normal and interchanged anticodon sequences. Transcripts containing wild-type tRNA sequences were excellent substrates for their respective cognate aminoacyl-tRNA synthetases and were effectively discriminated against by a variety of noncognate enzymes. The mutant tRNAs produced by switching the anticodon sequences lost their original tRNA identity and assumed an identity corresponding to the acquired anticodon sequence. These results indicate that the anticodon contains sufficient information to distinguish methionine and valine tRNAs with high fidelity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schulman, L H -- Pelka, H -- New York, N.Y. -- Science. 1988 Nov 4;242(4879):765-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Developmental Biology and Cancer, Albert Einstein College of Medicine, Bronx, New York 10461.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3055296" target="_blank"〉PubMed〈/a〉
    Keywords: *Anticodon ; Escherichia coli ; Kinetics ; Methionine-tRNA Ligase/metabolism ; *RNA, Transfer ; RNA, Transfer, Amino Acid-Specific/*physiology ; RNA, Transfer, Met/*physiology ; RNA, Transfer, Val/*physiology ; Substrate Specificity ; *Transfer RNA Aminoacylation ; Valine-tRNA Ligase/metabolism
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  • 37
    Publication Date: 1988-11-25
    Description: A cell-free translation system has been constructed that uses a continuous flow of the feeding buffer [including amino acids, adenosine triphosphate (ATP), and guanosine triphosphate (GTP)] through the reaction mixture and a continuous removal of a polypeptide product. Both prokaryotic (Escherichia coli) and eukaryotic (wheat embryos, Triticum sp.) versions of the system have been tested. In both cases the system has proven active for long times, synthesizing polypeptides at a high constant rate for tens of hours. With the use of MS2 phage RNA or brome mosaic virus RNA 4 as templates, 100 copies of viral coat proteins per RNA were synthesized for 20 hours in the prokaryotic or eukaryotic system, respectively. With synthetic calcitonin messenger RNA, 150 to 300 copies of calcitonin polypeptide were produced per messenger RNA in both types of continuous translation systems for 40 hours.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Spirin, A S -- Baranov, V I -- Ryabova, L A -- Ovodov, S Y -- Alakhov, Y B -- New York, N.Y. -- Science. 1988 Nov 25;242(4882):1162-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Protein Research, Academy of Sciences, Moscow Region, USSR.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3055301" target="_blank"〉PubMed〈/a〉
    Keywords: Bacteriophages/genetics ; Calcitonin/biosynthesis/genetics ; Capsid/biosynthesis/genetics ; Electrophoresis ; Escherichia coli/*metabolism ; Kinetics ; Mosaic Viruses/genetics ; *Peptide Biosynthesis ; Plants/*metabolism ; *Protein Biosynthesis ; RNA, Messenger/metabolism ; RNA, Viral/genetics ; Ribosomes/metabolism ; Templates, Genetic ; Triticum
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  • 38
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-01-08
    Description: The Bacillus subtilis ribonuclease P consists of a protein and an RNA. At high ionic strength the reaction is protein-independent; the RNA alone is capable of cleaving precursor transfer RNA, but the turnover is slow. Kinetic analyses show that high salt concentrations facilitate substrate binding in the absence of the protein, probably by decreasing the repulsion between the polyanionic enzyme and substrate RNAs, and also slow product release and enzyme turnover. It is proposed that the ribonuclease P protein, which is small and basic, provides a local pool of counter-ions that facilitates substrate binding without interfering with rapid product release.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Reich, C -- Olsen, G J -- Pace, B -- Pace, N R -- GM34527/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1988 Jan 8;239(4836):178-81.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Indiana University, Bloomington 47405.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3122322" target="_blank"〉PubMed〈/a〉
    Keywords: Bacillus subtilis/*enzymology ; Endoribonucleases/*physiology ; Kinetics ; Nucleic Acid Precursors/metabolism ; RNA, Transfer/metabolism ; Ribonuclease P ; Ribonucleoproteins/*physiology ; Structure-Activity Relationship
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  • 39
    Publication Date: 1988-12-16
    Description: The fidelity of protein biosynthesis in any cell rests on the accuracy of aminoacylation of tRNA. The exquisite specificity of this reaction is critically dependent on the correct recognition of tRNA by aminoacyl-tRNA synthetases. It is shown here that the relative concentrations of a tRNA and its cognate aminoacyl-tRNA synthetase are normally well balanced and crucial for maintenance of accurate aminoacylation. When Escherichia coli Gln-tRNA synthetase is overproduced in vivo, it incorrectly acylates the supF amber suppressor tRNA(Tyr) with Gln. This effect is abolished when the intracellular concentration of the cognate tRNA(Gln2) is also elevate. These data indicate that the presence of aminoacyl-tRNA synthetase and the cognate tRNAs in complexed form, which requires the proper balance of the two macromolecules, is critical in maintaining the fidelity of protein biosynthesis. Thus, limits exist on the relative levels of tRNAs and aminoacyl-tRNA synthetases within a cell.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Swanson, R -- Hoben, P -- Sumner-Smith, M -- Uemura, H -- Watson, L -- Soll, D -- New York, N.Y. -- Science. 1988 Dec 16;242(4885):1548-51.〈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/3144042" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acyl-tRNA Synthetases/genetics/*metabolism ; Escherichia coli/enzymology/*genetics ; Kinetics ; Plasmids ; RNA, Transfer, Amino Acid-Specific/*metabolism ; RNA, Transfer, Gln/*metabolism ; beta-Galactosidase/genetics/metabolism
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  • 40
    Publication Date: 1988-12-09
    Description: Potassium channels in neurons are linked by guanine nucleotide binding (G) proteins to numerous neurotransmitter receptors. The ability of Go, the predominant G protein in the brain, to stimulate potassium channels was tested in cell-free membrane patches of hippocampal pyramidal neurons. Four distinct types of potassium channels, which were otherwise quiescent, were activated by both isolated brain G0 and recombinant Go alpha. Hence brain Go can couple diverse brain potassium channels to neurotransmitter receptors.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉VanDongen, A M -- Codina, J -- Olate, J -- Mattera, R -- Joho, R -- Birnbaumer, L -- Brown, A M -- DK-19318/DK/NIDDK NIH HHS/ -- HL-31154/HL/NHLBI NIH HHS/ -- HL-37044/HL/NHLBI NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1988 Dec 9;242(4884):1433-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3144040" target="_blank"〉PubMed〈/a〉
    Keywords: Adenylyl Imidodiphosphate/pharmacology ; Animals ; Cattle ; Electric Conductivity ; GTP-Binding Proteins/*pharmacology ; Hippocampus/*physiology ; In Vitro Techniques ; Kinetics ; Macromolecular Substances ; Membrane Potentials/drug effects ; Potassium Channels/drug effects/*physiology ; Pyramidal Tracts/physiology ; Rats ; Recombinant Proteins/*pharmacology
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  • 41
    Publication Date: 1988-06-10
    Description: Proteins undergo a series of nonenzymatic reactions with glucose over time to form advanced glycosylation end products (AGEs). Macrophages have a receptor that recognizes the AGE moiety and mediates the uptake and degradation of AGE proteins. This removal process is associated with the production and secretion of cachectin (tumor necrosis factor) and interleukin-1, two cytokines with diverse and seemingly paradoxical biological activities. The localized release and action of these cytokines could account for the coordinated removal and replacement of senescent extracellular matrix components in normal tissue homeostasis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Vlassara, H -- Brownlee, M -- Manogue, K R -- Dinarello, C A -- Pasagian, A -- R01-AI15674/AI/NIAID NIH HHS/ -- R01-AM19655/AM/NIADDK NIH HHS/ -- R01-AM33861/AM/NIADDK NIH HHS/ -- New York, N.Y. -- Science. 1988 Jun 10;240(4858):1546-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Medical Biochemistry, Rockefeller University, New York, NY 10021.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3259727" target="_blank"〉PubMed〈/a〉
    Keywords: Glycosylation ; Humans ; Interleukin-1/*biosynthesis/genetics ; Kinetics ; Membrane Glycoproteins/*physiology ; Monocytes/*metabolism ; Protein Biosynthesis ; RNA, Messenger/genetics ; Tumor Necrosis Factor-alpha/*biosynthesis/genetics
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  • 42
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-06-17
    Description: Biochemical and electrophysiological studies suggest that adenosine 3',5'-monophosphate (cAMP)-dependent phosphorylation of the nicotinic acetylcholine receptor channel is functionally significant because it modifies the receptor's rate of desensitization to acetylcholine. In studies that support this conclusion researchers have used forskolin to stimulate cAMP-dependent phosphorylation in intact muscle. It is now shown that although forskolin facilitated desensitization in voltage-clamped rat muscle, this effect was not correlated with the abilities of forskolin and forskolin analogs to activate adenylate cyclase or phosphorylate the receptor. Furthermore, elevation of intracellular cAMP or addition of the catalytic subunit of A-kinase failed to alter desensitization. Therefore, in intact skeletal muscle, cAMP-dependent phosphorylation does not modulate desensitization.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wagoner, P K -- Pallotta, B S -- GM32211/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1988 Jun 17;240(4859):1655-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Pharmacology, Glaxo Research Laboratories, Chapel Hill, NC 27599.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2454507" target="_blank"〉PubMed〈/a〉
    Keywords: 1-Methyl-3-isobutylxanthine/pharmacology ; Acetylcholine/pharmacology ; Adenylyl Cyclases/metabolism ; Animals ; Bucladesine/pharmacology ; Colforsin/*pharmacology ; Cyclic AMP/analogs & derivatives/*pharmacology ; Electric Conductivity ; Enzyme Activation/drug effects ; Kinetics ; Muscles/*metabolism ; Phosphorylation ; Rats ; Receptors, Cholinergic/drug effects/*physiology ; Torpedo/metabolism
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  • 43
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-10-07
    Description: The enzymes adenosine 3',5'-monophosphate (cAMP)-dependent protein kinase (protein kinase A) and protein kinase C regulate the activity of a diverse group of cellular proteins including membrane ion channel proteins. When protein kinase A was stimulated in cardiac ventricular myocytes with the membrane-soluble cAMP analog 8-chlorphenylthio cAMP (8-CPT cAMP), the amplitude of the delayed-rectifier potassium current (IK) doubled when recorded at 32 degrees C but was not affected at 22 degrees C. In contrast, modulation of the calcium current (ICa) by 8-CPT cAMP was independent of temperature with similar increases in ICa occurring at both temperatures. Stimulation of protein kinase C by phorbol 12,13-dibutyrate also enhanced IK in a temperature-dependent manner but failed to increase ICa at either temperature. Thus, cardiac delayed-rectifier potassium but not calcium channels are regulated by two distinct protein kinases in a similar temperature-dependent fashion.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Walsh, K B -- Kass, R S -- New York, N.Y. -- Science. 1988 Oct 7;242(4875):67-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology, University of Rochester, School of Medicine and Dentistry, NY 14642.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2845575" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cyclic AMP/*analogs & derivatives/pharmacology ; Guinea Pigs ; Heart/*physiology ; Homeostasis ; In Vitro Techniques ; Kinetics ; Membrane Potentials ; Potassium Channels/*physiology ; Protein Kinase C/*metabolism ; Protein Kinases/*metabolism ; Thermodynamics ; Thionucleotides/*pharmacology ; Ventricular Function
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  • 44
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-12-16
    Description: The expression of a laboratory strain of HIV-1 (HTLV-IIIB) has been studied in mitogen-stimulated peripheral blood lymphocytes (PBLs) and in two lymphoid cell lines (CEM cells and C8166 cells). HIV-expressing cells contained from 300,000 to 2,500,000 copies of viral RNA per cell. Near-synchronous expression of an active infection could be achieved in C8166 cells. In these cells, the high copy numbers of viral RNA used as much as 40% of total protein synthesis for the production of viral gag protein, with high levels of viral RNA and protein synthesis preceding cell death by 2 to 4 days.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Somasundaran, M -- Robinson, H L -- AI 24474/AI/NIAID NIH HHS/ -- N01-HB-6-7022/HB/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1988 Dec 16;242(4885):1554-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology, University of Massachusetts Medical Center, Worcester 01655.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3201245" target="_blank"〉PubMed〈/a〉
    Keywords: Cell Line ; *Cell Transformation, Viral ; HIV-1/*genetics/growth & development/metabolism ; Humans ; Kinetics ; Lymphocytes/*microbiology ; RNA, Viral/*biosynthesis ; Viral Proteins/*biosynthesis
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  • 45
    Publication Date: 1988-03-18
    Description: The effects of lithium on inositol phosphate metabolism may account for the therapeutic actions of lithium in affective disorder. Muscarinic stimulation of the phosphoinositide system blocks synaptic inhibitory actions of adenosine in the hippocampal slice. At therapeutic concentrations, lithium diminished this muscarinic response, whereas rubidium, which does not affect phosphoinositide metabolism, had no effect. A dampening of phosphoinositide-mediated neurotransmission may explain the normalizing effects of lithium in treating both mania and depression.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Worley, P F -- Heller, W A -- Snyder, S H -- Baraban, J M -- DA-00266/DA/NIDA NIH HHS/ -- MH-18501/MH/NIMH NIH HHS/ -- MH-42323/MH/NIMH NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1988 Mar 18;239(4846):1428-9.〈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/2831626" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine/pharmacology ; Carbachol/pharmacology ; Enzyme Activation/drug effects ; Hippocampus/drug effects/*physiology ; Inositol Phosphates/metabolism ; Kinetics ; Lithium/*pharmacology ; Oxotremorine/analogs & derivatives/pharmacology ; Phorbol Esters/pharmacology ; Phosphatidylinositols/*metabolism ; Protein Kinase C/metabolism ; Receptors, Muscarinic/drug effects/*physiology ; Synapses/physiology ; Synaptic Transmission/drug effects
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  • 46
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-06-24
    Description: A specific, reversible binding site for a free amino acid is detectable on the intron of the Tetrahymena self-splicing ribosomal precursor RNA. The site selects arginine among the natural amino acids, and prefers the L- to the D-amino acid. The dissociation constant is in the millimolar range, and amino acid binding is at or in the catalytic rG splicing substrate site. Occupation of the G site by L-arginine therefore inhibits splicing by inhibiting the binding of rG, without inhibition of later reactions in the splicing reaction sequence. Arginine binding specificity seems to be directed at the side chain and the guanidino radical, and the alpha-amino and carboxyl groups are dispensable for binding. The arginine site can be placed within the G site by structural homology, with consequent implications for RNA-amino acid interaction, for the origin of the genetic code, for control of RNA activities, and for further catalytic capabilities for RNA.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yarus, M -- R37 GM30881/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1988 Jun 24;240(4860):1751-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder 80309.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3381099" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Arginine/*metabolism ; Binding Sites ; Catalysis ; Genetic Code ; Guanosine Triphosphate/metabolism ; Kinetics ; Magnesium/metabolism ; Models, Molecular ; *RNA Splicing ; RNA, Ribosomal/*physiology ; Structure-Activity Relationship ; Tetrahymena
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  • 47
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-02-12
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zeeberg, B R -- Gibson, R E -- Reba, R C -- MH42821-01/MH/NIMH NIH HHS/ -- NS-15080/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1988 Feb 12;239(4841 Pt 1):789-91.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2963379" target="_blank"〉PubMed〈/a〉
    Keywords: Brain/*metabolism ; Haloperidol/therapeutic use ; Humans ; Kinetics ; Receptors, Dopamine/drug effects/*metabolism ; Receptors, Dopamine D2 ; Schizophrenia/*metabolism
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  • 48
    Publication Date: 1988-02-05
    Description: The turnover of phosphatidylinositol 4,5-bisphosphate (PIP2) is believed to constitute a crucial step in the signaling pathways for stimulation of cells by a variety of bioactive substances, including mitogens, but decisive evidence for the idea has not been obtained. In the present study, a monoclonal antibody to PIP2 was microinjected into the cytoplasm of NIH 3T3 cells before or after exposure to mitogens. The antibody completely abolished nuclear labeling with [3H]thymidine induced by platelet-derived growth factor and bombesin, but not by fibroblast growth factor, epidermal growth factor, insulin, or serum. The findings strongly suggest that PIP2 breakdown is crucial in the elicitation and sustaining of cell proliferation induced by some types of mitogens such as platelet-derived growth factor and bombesin.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Matuoka, K -- Fukami, K -- Nakanishi, O -- Kawai, S -- Takenawa, T -- New York, N.Y. -- Science. 1988 Feb 5;239(4840):640-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pharmacology, Tokyo Metropolitan Institute of Gerontology, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2829356" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Antibodies, Monoclonal ; Antigen-Antibody Complex ; Bombesin/*pharmacology ; Cell Division/*drug effects ; Cells, Cultured ; Insulin/pharmacology ; Kinetics ; Mice ; Mice, Inbred Strains ; Phosphatidylinositol 4,5-Diphosphate ; Phosphatidylinositols/immunology/*physiology ; Platelet-Derived Growth Factor/*pharmacology
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  • 49
    Publication Date: 1988-02-26
    Description: Leader peptides that function to direct export of proteins through membranes have some common features but exhibit a remarkable sequence diversity. Thus there is some question whether leader peptides exert their function through conventional stereospecific protein-protein interaction. Here it is shown that the leader peptides retarded the folding of precursor maltose-binding protein and ribose-binding protein from Escherichia coli. This kinetic effect may be crucial in allowing precursors to enter the export pathway.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Park, S -- Liu, G -- Topping, T B -- Cover, W H -- Randall, L L -- GM29798/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1988 Feb 26;239(4843):1033-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Biochemistry/Biophysics Program, Washington State University, Pullman 99164.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3278378" target="_blank"〉PubMed〈/a〉
    Keywords: *ATP-Binding Cassette Transporters ; Bacterial Proteins/*metabolism ; Biological Transport ; Carrier Proteins/metabolism ; Endopeptidase K ; Escherichia coli/*metabolism ; *Escherichia coli Proteins ; Guanidine ; Guanidines/pharmacology ; Kinetics ; Maltose-Binding Proteins ; *Monosaccharide Transport Proteins ; Peptide Hydrolases ; *Periplasmic Binding Proteins ; *Protein Conformation/drug effects ; Protein Denaturation ; Protein Precursors/*metabolism ; Protein Sorting Signals/pharmacology/*physiology ; Serine Endopeptidases/pharmacology ; Spectrometry, Fluorescence
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  • 50
    Publication Date: 1988-10-14
    Description: Suspensions of thymocytes from young rats were incubated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), which resulted in a sustained increase in cytosolic free Ca2+ concentration followed by DNA fragmentation and loss of cell viability. Both the Ca2+ increase and DNA fragmentation were prevented in cells treated with the inhibitor of protein synthesis, cycloheximide, and DNA fragmentation and cell killing were not detected when cells were incubated in a "Ca2+-free" medium or pretreated with high concentrations of the calcium probe, quin-2 tetraacetoxymethyl ester. These results indicate that TCDD can kill immature thymocytes by initiating a suicide process similar to that previously described for glucocorticoid hormones.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉McConkey, D J -- Hartzell, P -- Duddy, S K -- Hakansson, H -- Orrenius, S -- New York, N.Y. -- Science. 1988 Oct 14;242(4876):256-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Toxicology, Karolinska Institutet, Stockholm, Sweden.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3262923" target="_blank"〉PubMed〈/a〉
    Keywords: Aminoquinolines ; Animals ; Calcium/metabolism/*pharmacology ; Cell Survival/drug effects ; Cycloheximide/pharmacology ; Cytosol/metabolism ; DNA/metabolism ; Deoxyribonuclease I/*metabolism ; Dioxins/*pharmacology ; Enzyme Activation/drug effects ; Fluorescent Dyes ; Glucocorticoids/pharmacology ; Kinetics ; Rats ; T-Lymphocytes/drug effects ; Tetrachlorodibenzodioxin/*pharmacology ; Thymus Gland/*drug effects/metabolism
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  • 51
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-04-29
    Description: The kinetics of calcium release by inositol 1,4,5-trisphosphate (IP3) in permeabilized rat basophilic leukemia cells were studied to obtain insight into the molecular mechanism of action of this intracellular messenger of the phosphoinositide cascade. Calcium release from intracellular storage sites was monitored with fura-2, a fluorescent indicator. The dependence of the rate of calcium release on the concentration of added IP3 in the 4 to 40 nM range showed that channel opening requires the binding of at least three molecules of IP3. Channel opening occurred in the absence of added adenosine triphosphate, indicating that IP3 acts directly on the channel or on a protein that gates it. The channels were opened by IP3 in less than 4 seconds. The highly cooperative opening of calcium channels by nanomolar concentrations of IP3 enables cells to detect and amplify very small changes in the concentration of this messenger in response to hormonal, sensory, and growth control stimuli.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Meyer, T -- Holowka, D -- Stryer, L -- AI22449/AI/NIAID NIH HHS/ -- GM24032/GM/NIGMS NIH HHS/ -- GM30387/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1988 Apr 29;240(4852):653-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cell Biology, Sherman Fairchild 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/2452482" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Basophils ; Benzofurans ; Calcimycin/pharmacology ; Calcium/*metabolism ; Cell Membrane Permeability ; Cytoplasm/metabolism ; Fluorescent Dyes ; Fura-2 ; Inositol 1,4,5-Trisphosphate ; Inositol Phosphates/metabolism/*pharmacology ; Ion Channels/drug effects/*metabolism ; Kinetics ; Leukemia, Experimental/metabolism ; Rats ; Spectrometry, Fluorescence ; Sugar Phosphates/*pharmacology ; Tumor Cells, Cultured
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  • 52
    Publication Date: 1988-10-21
    Description: Studies of the biology and pathogenesis of Kaposi's sarcoma (KS) have been hampered by the inability to maintain long-term cultures of KS cells in vitro. In this study AIDS-KS-derived cells with characteristic spindle-like morphology were cultured with a growth factor (or factors) released by CD4+ T lymphocytes infected with human T-lymphotropic virus type I or II (HTLV-I or HTLV-II) or with human immunodeficiency virus type 1 or 2 (HIV-1 or HIV-2). Medium conditioned by HTLV-II-infected, transformed lines of T cells (HTLV-II CM) contained large amounts of this growth activity and also supported the temporary growth of normal vascular endothelial cells, but not fibroblasts. Interleukin-1 and tumor necrosis factor-alpha stimulated the growth of the KS-derived cells, but the growth was only transient and these could be distinguished from that in HTLV-II CM. Other known endothelial cell growth promoting factors, such as acidic and basic fibroblast growth factors and epidermal growth factor, did not support the long-term growth of the AIDS-KS cells. The factor released by CD4+ T cells infected with human retroviruses should prove useful in studies of the pathogenesis of KS.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Nakamura, S -- Salahuddin, S Z -- Biberfeld, P -- Ensoli, B -- Markham, P D -- Wong-Staal, F -- Gallo, R C -- New York, N.Y. -- Science. 1988 Oct 21;242(4877):426-30.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Tumor Cell Biology, National Cancer Institute, Bethesda, MD 20892.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3262925" target="_blank"〉PubMed〈/a〉
    Keywords: Acquired Immunodeficiency Syndrome/immunology/*pathology ; Antigens, Differentiation, T-Lymphocyte/analysis ; Cell Division ; *Cell Transformation, Viral ; Growth Substances/*isolation & purification/physiology ; Human T-lymphotropic virus 1/*genetics ; Human T-lymphotropic virus 2/*genetics ; Humans ; Kinetics ; Sarcoma, Kaposi/*pathology ; T-Lymphocytes/*immunology ; Tumor Cells, Cultured
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  • 53
    Publication Date: 1988-11-11
    Description: Despite its potential toxicity, H2O2 is used as an extracellular oxidant by Stronglylocentrotus purpuratus eggs to cross-link their fertilization envelopes. These eggs contain 5 mM 1-methyl-N alpha,N alpha-dimethyl-4-mercaptohistidine (ovothiol C), which reacts with H2O2. In consuming H2O2 and being reduced by glutathione, ovothiol acts as a glutathione peroxidase and replaces the function of the enzyme in eggs. The ovothiol system is more effective than egg catalase in destroying H2O2 at concentrations produced during fertilization and constitutes a principal mechanism for preventing oxidative damage at fertilization.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Turner, E -- Hager, L J -- Shapiro, B M -- GM23910/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1988 Nov 11;242(4880):939-41.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, University of Washington, Seattle 98195.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3187533" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acids, Sulfur/*metabolism ; Animals ; Catalase/metabolism ; Disulfides/metabolism ; Female ; Fertilization ; Glutathione/metabolism ; Glutathione Peroxidase/*metabolism ; Kinetics ; *Methylhistidines ; NADP/metabolism ; Ovum/*metabolism ; Oxidation-Reduction ; Sea Urchins
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  • 54
    Publication Date: 1988-12-16
    Description: Three variations to the structure of the nicotinamide adenine dinucleotide (NAD)-dependent L-lactate dehydrogenase from Bacillus stearothermophilus were made to try to change the substrate specificity from lactate to malate: Asp197----Asn, Thr246----Gly, and Gln102----Arg). Each modification shifts the specificity from lactate to malate, although only the last (Gln102----Arg) provides an effective and highly specific catalyst for the new substrate. This synthetic enzyme has a ratio of catalytic rate (kcat) to Michaelis constant (Km) for oxaloacetate of 4.2 x 10(6)M-1 s-1, equal to that of native lactate dehydrogenase for its natural substrate, pyruvate, and a maximum velocity (250 s-1), which is double that reported for a natural malate dehydrogenase from B. stearothermophilus.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wilks, H M -- Hart, K W -- Feeney, R -- Dunn, C R -- Muirhead, H -- Chia, W N -- Barstow, D A -- Atkinson, T -- Clarke, A R -- Holbrook, J J -- New York, N.Y. -- Science. 1988 Dec 16;242(4885):1541-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, University of Bristol, United Kingdom.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3201242" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Geobacillus stearothermophilus/*enzymology/genetics ; Kinetics ; L-Lactate Dehydrogenase/*genetics/metabolism ; Malate Dehydrogenase/*metabolism ; Models, Molecular ; Protein Conformation ; Substrate Specificity
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  • 55
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-10-07
    Description: In vitro autoradiography with 125I-labeled melatonin was used to examine melatonin binding sites in human hypothalamus. Specific 125I-labeled melatonin binding was localized to the suprachiasmatic nuclei, the site of a putative biological clock, and was not apparent in other hypothalamic regions. Specific 125I-labeled melatonin binding was consistently found in the suprachiasmatic nuclei of hypothalami from adults and fetuses. Densitometric analysis of competition experiments with varying concentrations of melatonin showed monophasic competition curves, with comparable half-maximal inhibition values for the suprachiasmatic nuclei of adults (150 picomolar) and fetuses (110 picomolar). Micromolar concentrations of the melatonin agonist 6-chloromelatonin completely inhibited specific 125I-labeled melatonin binding, whereas the same concentrations of serotonin and norepinephrine caused only a partial reduction in specific binding. The results suggest that putative melatonin receptors are located in a human biological clock.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Reppert, S M -- Weaver, D R -- Rivkees, S A -- Stopa, E G -- HD06976/HD/NICHD NIH HHS/ -- HD14427/HD/NICHD NIH HHS/ -- U10-HD22297/HD/NICHD NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1988 Oct 7;242(4875):78-81.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Developmental Chronobiology, Boston.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2845576" target="_blank"〉PubMed〈/a〉
    Keywords: Autoradiography ; Binding, Competitive ; *Biological Clocks ; Humans ; Hypothalamus/*metabolism ; Iodine Radioisotopes ; Kinetics ; Melatonin/*metabolism ; Optic Chiasm/metabolism ; Receptors, Melatonin ; Receptors, Neurotransmitter/*physiology ; Suprachiasmatic Nucleus/metabolism ; Supraoptic Nucleus/metabolism
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  • 56
    Publication Date: 1988-08-12
    Description: Calcium channels are inactivated by voltage and intracellular calcium. To study the kinetics and the mechanism of calcium-induced inactivation of calcium channels, a "caged" calcium compound, dimethoxy-nitrophen was used to photo-release about 50 microM calcium ion within 0.2 millisecond in dorsal root ganglion neurons. When divalent cations were the charge carriers, intracellular photo-release of calcium inactivated the calcium channel with an invariant rate [time constant (tau) approximately equal to 7 milliseconds]. When the monovalent cation sodium was the charge carrier, photorelease of calcium inside or outside of the cell blocked the channel rapidly (tau approximately equal to 0.4 millisecond), but the block was greater from the external side. Thus the kinetics of calcium-induced calcium channel inactivation depends on the valency of the permeant cation. The data imply that calcium channels exist in either of two conformational states, the calcium- and sodium-permeant forms, or, alternatively, calcium-induced inactivation occurs at a site closely associated with the internal permeating site.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Morad, M -- Davies, N W -- Kaplan, J H -- Lux, H D -- R01 HL-16152/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1988 Aug 12;241(4867):842-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉University of Pennsylvania, Department of Physiology, Philadelphia 19104-6085.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2457253" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Calcium/*physiology/radiation effects ; Cells, Cultured ; Chickens ; Ganglia, Spinal/*physiology/radiation effects ; Ion Channels/*physiology ; Kinetics ; Neurons/*physiology/radiation effects ; Photolysis ; Sodium/metabolism ; *Ultraviolet Rays
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  • 57
    Publication Date: 1988-11-11
    Description: Manganous superoxide dismutase (MnSOD) scavenges potentially toxic superoxide radicals produced in the mitochondria. Tumor necrosis factor-alpha (TNF-alpha) was found to induce the messenger RNA for MnSOD, but not the mRNAs for other antioxidant or mitochondrial enzymes tested. The increase in MnSOD mRNA occurred rapidly and was blocked by actinomycin D, but not by cycloheximide. Induction of MnSOD mRNA was also observed with TNF-beta, interleukin-1 alpha (IL-1 alpha), and IL-1 beta but not with other cytokines or agents tested. TNF-alpha induced MnSOD mRNA in all cell lines and normal cells examined in vitro and in various organs of mice in vivo. These effects of TNF-alpha and IL-1 on target cells may contribute to their reported protective activity against radiation as well as their ability to induce resistance to cell killing induced by the combination of TNF-alpha and cycloheximide.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wong, G H -- Goeddel, D V -- New York, N.Y. -- Science. 1988 Nov 11;242(4880):941-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, Genentech, San Francisco, CA 94080.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3263703" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Catalase/metabolism ; Cell Line ; Cycloheximide/pharmacology ; Dactinomycin/pharmacology ; Enzyme Induction/drug effects ; Humans ; Interleukin-1/pharmacology ; Kinetics ; Mice ; Mitochondria/enzymology ; RNA, Messenger/biosynthesis ; Rats ; Superoxide Dismutase/*biosynthesis/genetics/metabolism ; Tissue Distribution ; Tumor Necrosis Factor-alpha/*pharmacology
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  • 58
    Publication Date: 1988-03-04
    Description: Kinetic analysis and protein mutagenesis allow the importance of individual amino acids in ligand binding and catalysis to be assessed. A kinetic analysis has shown that the reaction catalyzed by dihydrofolate reductase is optimized with respect to product flux, which in turn is predetermined by the active-site hydrophobic surface. Protein mutagenesis has revealed that specific hydrophobic residues contribute 2 to 5 kilocalories per mole to ligand binding and catalysis. The extent to which perturbations within this active-site ensemble may affect catalysis is discussed in terms of the constraints imposed by the energy surface for the reaction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Benkovic, S J -- Fierke, C A -- Naylor, A M -- GM24129/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1988 Mar 4;239(4844):1105-10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Pennsylvania State University, University Park 16802.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3125607" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Catalysis ; Chemical Phenomena ; Chemistry ; Escherichia coli/enzymology ; Kinetics ; Lactobacillus casei/enzymology ; *Mutation ; Structure-Activity Relationship ; Tetrahydrofolate Dehydrogenase/genetics/*metabolism ; Thermodynamics
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  • 59
    Publication Date: 1988-08-12
    Description: The interaction between receptors and guanine nucleotide binding (G) proteins leads to G protein activation and subsequent regulation of effector enzymes. The molecular basis of receptor-G protein interaction has been examined by using the ability of the G protein from rods (transducin) to cause a conformational change in rhodopsin as an assay. Synthetic peptides corresponding to two regions near the carboxyl terminus of the G protein alpha subunit, Glu311-Val328 and Ile340-Phe350, compete with G protein for interaction with rhodopsin. Amino acid substitution studies show that Cys321 is required for this effect. Ile340-Phe350 and a modified peptide, acetyl-Glu311-Lys329-amide, mimic G protein effects on rhodopsin conformation, showing that these peptides bind to and stabilize the activated conformation of rhodopsin.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hamm, H E -- Deretic, D -- Arendt, A -- Hargrave, P A -- Koenig, B -- Hofmann, K P -- EY06062/EY/NEI NIH HHS/ -- EY06225/EY/NEI NIH HHS/ -- RP05369/PHS HHS/ -- etc. -- New York, N.Y. -- Science. 1988 Aug 12;241(4867):832-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology and Biophysics, University of Illinois College of Medicine, Chicago 60680.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3136547" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Antibodies, Monoclonal ; Antigen-Antibody Complex ; Binding Sites ; GTP-Binding Proteins/*metabolism ; Kinetics ; Macromolecular Substances ; Membrane Proteins/*metabolism ; Peptides/metabolism ; Protein Binding ; Protein Conformation ; Retinal Pigments/*metabolism ; Rhodopsin/analogs & derivatives/*metabolism ; Transducin
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  • 60
    Publication Date: 1988-09-02
    Description: Catalysis of amide bond hydrolysis is of singular importance in enzymology. An antibody was induced to an analog of a high-energy intermediate anticipated along the reaction coordinate of amide hydrolysis. This antibody is an amidase with high specificity and a large rate enhancement (250,000) relative to the uncatalyzed reaction. This reaction represents the kinetically most difficult hydrolysis reaction yet catalyzed by an antibody.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Janda, K D -- Schloeder, D -- Benkovic, S J -- Lerner, R A -- New York, N.Y. -- Science. 1988 Sep 2;241(4870):1188-91.〈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/3413482" target="_blank"〉PubMed〈/a〉
    Keywords: Amidohydrolases/metabolism ; Animals ; Antibodies, Monoclonal/biosynthesis/*physiology ; Antibody Specificity ; Antigens/immunology ; *Catalysis ; Chemical Phenomena ; Chemistry ; Hemocyanin/analogs & derivatives/immunology ; Hydrolysis ; Immunization ; Kinetics ; Mice ; Organophosphorus Compounds/immunology ; Substrate Specificity
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  • 61
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-08-12
    Description: Receptors for N-methyl-D-aspartate (NMDA) are involved in many plastic and pathological processes in the brain. Glycine has been reported to potentiate NMDA responses in neurons and in Xenopus oocytes injected with rat brain messenger RNA. Glycine is now shown to be absolutely required for activation of NMDA receptors in oocytes. In voltage-clamped oocytes, neither perfusion nor rapid pressure application of NMDA onto messenger RNA-injected oocytes caused a distinct ionic current without added glycine. When glycine was added, however, NMDA evoked large inward currents. The concentration of glycine required to produce a half-maximal response was 670 nanomolar, and the glycine dose-response curve extrapolated to zero in the absence of glycine. Several analogs of glycine could substitute for glycine, among which D-serine and D-alanine were the most effective. The observation that D-amino acids are effective will be important in developing drugs targeted at the glycine site.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kleckner, N W -- Dingledine, R -- NS17771/NS/NINDS NIH HHS/ -- NS22249/NS/NINDS NIH HHS/ -- NS23804/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1988 Aug 12;241(4867):835-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pharmacology, University of North Carolina, Chapel Hill 27599-7365.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2841759" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acids/pharmacology ; Animals ; Brain/metabolism ; Female ; Glycine/*analogs & derivatives/*pharmacology ; Kinetics ; Oocytes/drug effects/*metabolism ; RNA, Messenger/genetics ; Rats ; Receptors, N-Methyl-D-Aspartate ; Receptors, Neurotransmitter/drug effects/genetics/*metabolism ; Xenopus
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  • 62
    Publication Date: 1988-06-10
    Description: Clinical and seroepidemiological studies in West Africa indicate that human immunodeficiency virus type 2 (HIV-2) is widespread and associated with immunodeficiency states of variable degree. In this study, an isolate of HIV-2 from a patient in Senegal was molecularly cloned and characterized. This isolate (HIV-2ST) was shown by hybridization and restriction enzyme analysis to be more related to the prototype HIV-2ROD than to other human or primate retroviruses. Cultures of HIV-2ST showed genotypic polymorphism, and clones of the virus had transmembrane envelope glycoproteins of 30 and 42 kilodaltons. Unlike other immunodeficiency viruses, HIV-2ST did not cause cell death or induce cell fusion in peripheral blood lymphocytes or in any of four CD4+ cell lines tested. Although HIV-2ST entered cells by a CD4-dependent mechanism and replicated actively, cell-free transmission of the virus was retarded at the level of cell entry. These findings suggest that immunodeficiency viruses prevalent in West African populations are members of the HIV-2 virus group and that certain strains of this virus have attenuated virulence.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kong, L I -- Lee, S W -- Kappes, J C -- Parkin, J S -- Decker, D -- Hoxie, J A -- Hahn, B H -- Shaw, G M -- New York, N.Y. -- Science. 1988 Jun 10;240(4858):1525-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Internal Medicine, University of Alabama, Birmingham 35294.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3375832" target="_blank"〉PubMed〈/a〉
    Keywords: Cell Line ; Cell Survival ; DNA, Viral/genetics ; Genes, Viral ; HIV/classification/*isolation & purification/pathogenicity ; Humans ; Kinetics ; Lymphocytes/microbiology ; Senegal ; Species Specificity
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  • 63
    Publication Date: 1988-12-16
    Description: Site-directed mutagenesis and expression in Xenopus oocytes were used to study acetylcholine receptors in which serine residues (i) were replaced by alanines (alpha, delta subunits) or (ii) replaced a phenylalanine (beta subunit) at a postulated polar site within the M2 transmembrane helix. As the number of serines decreased, there were decreases in the residence time and consequently the equilibrium binding affinity of QX-222, a quaternary ammonium anesthetic derivative thought to bind within the open channel. Receptors with three serine-to-alanine mutations also displayed a selective decrease in outward single-channel currents. Both the direction of this rectification and the voltage dependence of QX-222 blockade suggest that the residues mutated are within the aqueous pore of the receptor and near its cytoplasmic (inner) surface.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Leonard, R J -- Labarca, C G -- Charnet, P -- Davidson, N -- Lester, H A -- NS-11756/NS/NINDS NIH HHS/ -- NS-8083/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1988 Dec 16;242(4885):1578-81.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Biology, California Institute of Technology, Pasadena 91125.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2462281" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Membrane/*physiology ; Cloning, Molecular ; Electric Conductivity ; Female ; Ion Channels/*physiology ; Kinetics ; Membrane Potentials ; Mutation ; Oocytes/physiology ; RNA, Messenger/genetics ; Receptors, Nicotinic/genetics/*physiology ; Transcription, Genetic ; Xenopus
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  • 64
    Publication Date: 1988-04-01
    Description: A mutant catalytic subunit of adenosine 3',5'-monophosphate (cAMP)-dependent protein kinase has been isolated from Saccharomyces cerevisiae that is no longer subject to regulation yet retains its catalytic activity. Biochemical analysis of the mutant subunit indicates a 100-fold decreased affinity for the regulatory subunit. The mutant catalytic subunit exhibits approximately a threefold increase in Michaelis constant for adenosine triphosphate and peptide cosubstrates, and is essentially unchanged in its catalytic rate. The nucleotide sequence of the mutant gene contains a single nucleotide change resulting in a threonine-to-alanine substitution at amino acid 241. This residue is conserved in other serine-threonine protein kinases. These results identify this threonine as an important contact between catalytic and regulatory subunits but only a minor contact in substrate recognition.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Levin, L R -- Kuret, J -- Johnson, K E -- Powers, S -- Cameron, S -- Michaeli, T -- Wigler, M -- Zoller, M J -- GM33986/GM/NIGMS NIH HHS/ -- R35 CA39829-02/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1988 Apr 1;240(4848):68-70.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Cold Spring Harbor Laboratory, NY 11724.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2832943" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Catalysis ; Cyclic AMP/*pharmacology ; Genes, Fungal ; Kinetics ; Macromolecular Substances ; Molecular Sequence Data ; Mutation ; Phosphorylation ; Protein Kinases/*genetics/metabolism ; Saccharomyces cerevisiae/enzymology/*genetics ; Structure-Activity Relationship ; Threonine
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  • 65
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-09-02
    Description: Two groups of mediators, the neuropeptides substance P and K and the monocyte-derived cytokines, interact in the neural regulation of immunological and inflammatory responses. Substance P, substance K, and the carboxyl-terminal peptide SP(4-11) induce the release of interleukin-1, tumor necrosis factor-alpha, and interleukin-6 from human blood monocytes. The neuropeptide effects occur at low doses, are specific as shown by inhibition studies with a substance P antagonist, and require de novo protein synthesis. Since monocyte-derived cytokines regulate multiple cellular functions in inflammation and immunity and since neuropeptides can be released from peripheral nerve endings into surrounding tissues, these findings identify a potent mechanism for nervous system regulation of host defense responses.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lotz, M -- Vaughan, J H -- Carson, D A -- AI10386/AI/NIAID NIH HHS/ -- AR21175/AR/NIAMS NIH HHS/ -- AR25443/AR/NIAMS NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1988 Sep 2;241(4870):1218-21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Basic and Clinical Research, 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/2457950" target="_blank"〉PubMed〈/a〉
    Keywords: Cells, Cultured ; Humans ; Interleukin-1/biosynthesis ; Interleukin-6 ; Interleukins/*biosynthesis ; Kinetics ; Monocytes/drug effects/immunology/*metabolism ; Neurokinin A ; Neuropeptides/*pharmacology ; Protein Biosynthesis ; Substance P/pharmacology ; Tumor Necrosis Factor-alpha/*biosynthesis
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  • 66
    Publication Date: 1988-04-15
    Description: Yeast iso-1-cytochrome c (Cc) mutants have been constructed with Phe, Tyr, Gly, Ser, Leu, and Ile at position 82, each with Thr substituted for Cys at position 102. Their long-range electron transfer with zinc-substituted cytochrome c peroxidase (ZnCcP) has been studied by two kinetic techniques. The charge-separated complex, [(ZnCcP)+,FeIICc] converts to [ZnCcP,FeIIICc] by a single, intracomplex electron transfer step that is not governed by "gating" through possible rapid dissociation of the complex or isomerization (for example, heme-ligand) by FeIICc subsequent to its formation from FeIIICc. In every variant with an aliphatic residue at position 82 of Cc, the rate of this electron transfer process is approximately 10(4) slower at approximately 0 degrees C than for the two variants with aromatic residues.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Liang, N -- Mauk, A G -- Pielak, G J -- Johnson, J A -- Smith, M -- Hoffman, B M -- GM-33804/GM/NIGMS NIH HHS/ -- HL-13531/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1988 Apr 15;240(4850):311-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Northwestern University, Evanston, IL 60208.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2832950" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acids ; Cytochrome c Group/*metabolism ; Cytochrome-c Peroxidase/*metabolism ; *Cytochromes c ; Electron Transport ; Genetic Variation ; Kinetics ; Peroxidases/*metabolism ; Photolysis ; Saccharomyces cerevisiae/metabolism ; *Saccharomyces cerevisiae Proteins
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  • 67
    Publication Date: 1988-10-07
    Description: In the sarcoplasmic reticulum membrane of skeletal muscle, the ryanodine receptor forms an aqueous pore identified as the calcium-release pathway that operates during excitation-contraction coupling. The purified ryanodine receptor channel has now been shown to have four properties usually associated with gap junction channels: (i) a large nonspecific voltage-dependent conductance consisting of several open states; (ii) an inhibition of open probability by low pH; (iii) an inhibition of open probability by calcium; and (iv) a sensitivity to blockade by heptanol and octanol but not other alcohols. This functional homology may provide an insight into the mechanism of how muscle cells transduce depolarization into an intracellular release of calcium.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ma, J -- Fill, M -- Knudson, C M -- Campbell, K P -- Coronado, R -- GM 36852/GM/NIGMS NIH HHS/ -- HL 37044/HL/NHLBI NIH HHS/ -- HL 39262/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1988 Oct 7;242(4875):99-102.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2459777" target="_blank"〉PubMed〈/a〉
    Keywords: Alcohols/pharmacology ; Animals ; Electric Conductivity ; Intercellular Junctions/*physiology ; Ion Channels/drug effects/*physiology ; Kinetics ; Membrane Potentials ; Muscles/*physiology ; Receptors, Cholinergic/drug effects/isolation & purification/*physiology ; Ryanodine/metabolism/pharmacology ; Ryanodine Receptor Calcium Release Channel ; Sarcoplasmic Reticulum/physiology
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  • 68
    Publication Date: 1988-10-07
    Description: Brief repetitive activation of excitatory synapses in the hippocampus leads to an increase in synaptic strength that lasts for many hours. This long-term potentiation (LTP) of synaptic transmission is the most compelling cellular model in the vertebrate brain for learning and memory. The critical role of postsynaptic calcium in triggering LTP has been directly examined using three types of experiment. First, nitr-5, a photolabile nitrobenzhydrol tetracarboxylate calcium chelator, which releases calcium in response to ultraviolet light, was used. Photolysis of nitr-5 injected into hippocampal CA1 pyramidal cells resulted in a large enhancement of synaptic transmission. Second, in agreement with previous results, buffering intracellular calcium at low concentrations blocked LTP. Third, depolarization of the postsynaptic membrane so that calcium entry is suppressed prevented LTP. Taken together, these results demonstrate that an increase in postsynaptic calcium is necessary to induce LTP and sufficient to potentiate synaptic transmission.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Malenka, R C -- Kauer, J A -- Zucker, R S -- Nicoll, R A -- MH00437/MH/NIMH NIH HHS/ -- MH38256/MH/NIMH NIH HHS/ -- NS24205/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1988 Oct 7;242(4875):81-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pharmacology, School of Medicine, University of California, San Francisco 94143.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2845577" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Calcium/*physiology ; Chelating Agents/pharmacology ; Egtazic Acid/analogs & derivatives/pharmacology ; Evoked Potentials/drug effects ; Hippocampus/*physiology ; In Vitro Techniques ; Kinetics ; Photolysis ; Pyramidal Tracts/physiology ; Rats ; Synapses/*physiology ; *Synaptic Transmission
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  • 69
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-10-28
    Description: In cells that do not express immunoglobulin kappa light chain genes, the kappa enhancer binding protein NF-kappa B is found in cytosolic fractions and exhibits DNA binding activity only in the presence of a dissociating agent such as sodium deoxycholate. The dependence on deoxycholate is shown to result from association of NF-kappa B with a 60- to 70-kilodalton inhibitory protein (I kappa B). The fractionated inhibitor can inactivate NF-kappa B from various sources--including the nuclei of phorbol ester-treated cells--in a specific, saturable, and reversible manner. The cytoplasmic localization of the complex of NF-kappa B and I kappa B was supported by enucleation experiments. An active phorbol ester must therefore, presumably by activation of protein kinase C, cause dissociation of a cytoplasmic complex of NF-kappa B and I kappa B by modifying I kappa B. this releases active NF-kappa B which can translocate into the nucleus to activate target enhancers. The data show the existence of a phorbol ester-responsive regulatory protein that acts by controlling the DNA binding activity and subcellular localization of a transcription factor.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Baeuerle, P A -- Baltimore, D -- New York, N.Y. -- Science. 1988 Oct 28;242(4878):540-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Whitehead Institute for Biomedical Research, MA 02142.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3140380" target="_blank"〉PubMed〈/a〉
    Keywords: B-Lymphocytes/physiology ; Cytoplasm/physiology ; DNA-Binding Proteins/physiology ; Enhancer Elements, Genetic ; *Gene Expression Regulation/drug effects ; Humans ; Immunoglobulin kappa-Chains/*genetics ; Kinetics ; Molecular Structure ; Molecular Weight ; Protein Binding ; Regulatory Sequences, Nucleic Acid ; Tetradecanoylphorbol Acetate/pharmacology ; Transcription Factors/*antagonists & inhibitors/physiology
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  • 70
    Publication Date: 1988-05-20
    Description: Immunization with a 41-kilodalton blood stage antigen (p41) of Plasmodium falciparum induces immunity to malaria in monkeys. However, antigenic polymorphism and repetitive amino acids commonly found in protective antigens complicate vaccine development. The gene encoding p41 has now been cloned and analyzed. Sequencing and hybridization studies revealed that the gene structure is highly conserved in 14 parasite isolates from three continents. This finding and the lack of repetitive amino acids in the translated DNA sequence may indicate that p41 has an essential function. In this study the protein was found to be 60 percent homologous to the key glycolytic enzyme aldolase from vertebrates, and the affinity-purified p41 protein from parasites showed aldolase activity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Certa, U -- Ghersa, P -- Dobeli, H -- Matile, H -- Kocher, H P -- Shrivastava, I K -- Shaw, A R -- Perrin, L H -- New York, N.Y. -- Science. 1988 May 20;240(4855):1036-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Central Research Units, F. Hoffmann-La Roche and Co., Basel, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3285469" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antibodies, Protozoan/immunology ; Antigen-Antibody Complex/analysis ; Antigens, Protozoan/genetics/*immunology ; Fructose-Bisphosphate Aldolase/genetics/immunology/*metabolism ; Kinetics ; Plasmodium falciparum/enzymology/*immunology ; Polymorphism, Genetic
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  • 71
    Publication Date: 1988-02-26
    Description: Patch clamp recordings of whole-cell and single channel currents revealed the presence of two voltage-sensitive calcium channel types in the membrane of 3T3 fibroblasts. The two calcium channel types were identified by their unitary properties and pharmacological sensitivities. Both calcium channel types were present in all control 3T3 cells, but one type was selectively suppressed in 3T3 cells that had been transformed by activated c-H-ras, EJ-ras, v-fms, or polyoma middle T oncogenes. The presence of voltage-sensitive calcium channels in these nonexcitable cells and the control of their functional expression by transforming oncogenes raises questions about their role in the control of calcium-sensitive processes such as cell motility, cytoskeletal organization, and cell growth.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chen, C F -- Corbley, M J -- Roberts, T M -- Hess, P -- CA21082/CA/NCI NIH HHS/ -- HL37124/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1988 Feb 26;239(4843):1024-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology, Harvard Medical School, Boston, MA 02115.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2449730" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Calcium/*metabolism ; Calcium Channel Agonists ; Cell Division ; Cell Line ; Cell Line, Transformed ; *Cell Transformation, Neoplastic ; Electric Conductivity ; Fibroblasts/*physiology ; Ion Channels/drug effects/*physiology ; Kinetics ; Membrane Potentials ; Mice ; Nicotinic Acids/pharmacology ; Oncogenes ; *Oxadiazoles
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  • 72
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-10-07
    Description: Adhesion of blood cells to endothelial cells is an essential component of all inflammatory responses. The capacity of the endothelium to support adhesion of neutrophils is increased by cytokines such as tumor necrosis factor-alpha, interleukin-1, and endotoxin. Another cytokine, transforming growth factor-beta (TGF-beta), was a strong inhibitor of basalneutrophil adhesion and also decreased the adhesive response of endothelial cells to tumor necrosis factor-alpha (TNF-alpha). The ability of cells to respond to TGF-beta was related to the duration of culture of endothelial cells after explantation from umbilical veins. TGF-beta is likely to serve an anti-inflammatory role at sites of blood vessel injury undergoing active endothelial regeneration.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gamble, J R -- Vadas, M A -- New York, N.Y. -- Science. 1988 Oct 7;242(4875):97-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Human Immunology, Institute of Medical and Veterinary Science, Adelaide, South Australia.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3175638" target="_blank"〉PubMed〈/a〉
    Keywords: Cell Adhesion/drug effects ; Cells, Cultured ; Endothelium, Vascular/cytology/drug effects/*physiology ; Humans ; Kinetics ; Neutrophils/cytology/drug effects/*physiology ; Transforming Growth Factors/*pharmacology ; Umbilical Veins
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  • 73
    Publication Date: 1988-04-22
    Description: The three-dimensional structure of most enzymes is unknown; however, many enzymes may have structural motifs similar to those in the known structures of functionally related enzymes. Evidence is presented that an enzyme of unknown structure [Ile-transfer RNA (tRNA) synthetase] may share a functionally important structural motif with an enzyme of related function (Tyr-tRNA synthetase). This approach involves (i) identifying segments of Ile-tRNA synthetase that have been unusually conserved during evolution, (ii) predicting the function of one such segment by assuming a structural relation between Ile-tRNA synthetase and Tyr-tRNA synthetase, and (iii) testing the predicted function by mutagenesis and subsequent biochemical analysis. Random mutations were introduced by cassette mutagenesis into a ten-amino-acid segment of Ile-tRNA synthetase that was predicted to be involved in the formation of the binding site for isoleucine. Few amino acid substitutions appear to be tolerated in this region. However, one substitution (independently isolated twice) increased the Michaelis constant Km for isoleucine in the adenylate synthesis reaction by greater than 6000-fold, but had little effect on the Km for adenosine triphosphate, the apparent Km for tRNA, or the rate constant kcat.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Clarke, N D -- Lien, D C -- Schimmel, P -- GM15539/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1988 Apr 22;240(4851):521-3.〈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/3282306" target="_blank"〉PubMed〈/a〉
    Keywords: *Amino Acyl-tRNA Synthetases ; Binding Sites ; DNA Mutational Analysis ; Escherichia coli/enzymology ; *Isoleucine-tRNA Ligase ; Kinetics ; Protein Conformation ; Saccharomyces cerevisiae/enzymology ; Structure-Activity Relationship
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  • 74
    Publication Date: 1988-03-11
    Description: A complementary DNA encoding the human low density lipoprotein (LDL) receptor under control of the mouse metallothionein-I promoter was injected into fertilized mouse eggs, and a strain of mice expressing high levels of LDL receptors was established. After administration of cadmium, these mice cleared intravenously injected 125I-labeled LDL from blood eight to ten times more rapidly than did normal mice. The plasma concentrations of apoproteins B-100 and E, the two ligands for the LDL receptor, declined by more than 90 percent after cadmium treatment, but the concentration of another apoprotein, A-I, was unaffected. Therefore, overexpression of an endocytotic receptor can dramatically lower the ambient concentration of its ligand in vivo.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hofmann, S L -- Russell, D W -- Brown, M S -- Goldstein, J L -- Hammer, R E -- HL 01287/HL/NHLBI NIH HHS/ -- HL 20948/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1988 Mar 11;239(4845):1277-81.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas 75235.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3344433" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cloning, Molecular ; DNA/genetics ; Female ; *Genes ; Humans ; Kinetics ; Lipoproteins, LDL/*blood ; Mice ; Mice, Transgenic ; Plasmids ; Receptors, LDL/*genetics/metabolism ; Reference Values ; Transcription, Genetic
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  • 75
    Publication Date: 1988-06-10
    Description: The proliferating cell nuclear antigen (PCNA or cyclin) is a nuclear protein recently identified as a cofactor of DNA polymerase delta. When exponentially growing Balb/c3T3 cells are exposed to antisense oligodeoxynucleotides to PCNA, both DNA synthesis and mitosis are completely suppressed. A corresponding sense oligodeoxynucleotide has no inhibitory effects. These experiments indicate that PCNA (cyclin) is important in cellular DNA synthesis and in cell cycle progression.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jaskulski, D -- deRiel, J K -- Mercer, W E -- Calabretta, B -- Baserga, R -- CA 42866/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1988 Jun 10;240(4858):1544-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology, Temple University Medical School, Philadelphia, PA 19140.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2897717" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Autoantigens/*genetics ; Base Sequence ; Cell Division/drug effects ; Cells, Cultured ; Codon ; DNA Replication/*drug effects ; Kinetics ; Mice ; Mice, Inbred BALB C ; Mitosis/*drug effects ; Molecular Sequence Data ; Nuclear Proteins/*genetics ; Oligodeoxyribonucleotides/*pharmacology ; Proliferating Cell Nuclear Antigen
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  • 76
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-07-01
    Description: Synthetic DNA oligomers (tDNAs) corresponding to Escherichia coli tRNA(Phe) or tRNA(Lys) have been synthesized with either deoxythymidine (dT) or deoxyuridine (dU) substituted in the positions occupied by ribouridine or its derivatives. The tDNAs inhibited the aminoacylation of their respective tRNAs with their cognate amino acids, but not the aminoacylation of tRNA(Leu) with Leu. In the presence of aminoacyl-tRNA synthetase, species of both a tDNA(Phe) synthesized with a 3' terminal riboadenosine and a tDNA(Lys) containing only deoxynucleotides could be aminoacylated with the appropriate amino acids, although the Michaelis constant Km and observed maximal rate Vmax values for aminoacylation were increased by three- to fourfold and decreased by two- to threefold, respectively. The aminoacylation of synthetic tDNAs demonstrates that the ribose backbone of a tRNA is not absolutely required for tRNA aminoacylation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Khan, A S -- Roe, B A -- GM-30400/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1988 Jul 1;241(4861):74-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of Oklahoma, Norman 73019.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2455342" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; DNA/genetics/*metabolism ; Deoxyuridine/metabolism ; Dimethyl Sulfoxide/pharmacology ; Escherichia coli/*genetics ; Hydrogen-Ion Concentration ; Kinetics ; Lysine-tRNA Ligase/metabolism ; Molecular Sequence Data ; Phenylalanine-tRNA Ligase/metabolism ; RNA, Bacterial/*genetics ; RNA, Transfer, Amino Acyl/*genetics ; Spermidine/pharmacology ; Structure-Activity Relationship ; Thymidine/metabolism
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  • 77
    Publication Date: 1988-10-14
    Description: Several new synthetic agents show high affinity for binding adenine derivatives. The structures feature complementary hydrogen bonds that cause the molecular chelation of the purine nucleus. The high lipophilicity of the new agents permits the transport of adenosine and deoxyadenosine across organic liquid membranes. The use of synthetic receptors for small biological targets may have application in drug delivery.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Benzing, T -- Tjivikua, T -- Wolfe, J -- Rebek, J Jr -- New York, N.Y. -- Science. 1988 Oct 14;242(4876):266-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of Pittsburgh, PA 15260.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3262924" target="_blank"〉PubMed〈/a〉
    Keywords: Adenine/analogs & derivatives/*metabolism ; Biological Transport ; Chloroform ; Deoxyadenosines/metabolism ; *Drug Carriers ; Hydrogen Bonding ; Kinetics ; Membranes, Artificial ; Molecular Structure
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  • 78
    Publication Date: 1988-06-10
    Description: The human platelet-derived growth factor (PDGF) receptor complementary DNA was cloned and expressed by transfection of Chinese hamster ovary (CHO) fibroblasts. The ability of CHO cells expressing the human receptor complementary DNA (CHO-HR5) to interact with different recombinant forms of PDGF (AA and BB homodimers) was tested. Both forms of PDGF bind to the transfected receptor, stimulate the receptor tyrosine kinase activity, and elicit a mitogenic response in a manner that was indistinguishable from the responses of Balb/c 3T3 cells to AA and BB forms of PDGF can be attributed to a single type of receptor and show that the AA form, like the BB form, is a true mitogen.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Escobedo, J A -- Navankasatussas, S -- Cousens, L S -- Coughlin, S R -- Bell, G I -- Williams, L T -- HL-32898/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1988 Jun 10;240(4858):1532-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Medicine, University of California, San Francisco.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2836953" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Division/drug effects ; Cell Line ; Cells, Cultured ; DNA Replication/drug effects ; Enzyme Activation ; Humans ; Kinetics ; Macromolecular Substances ; Mice ; Phosphorylation ; Platelet-Derived Growth Factor/genetics/*metabolism/pharmacology ; Protein-Tyrosine Kinases/*metabolism ; Receptors, Cell Surface/genetics/*metabolism ; Receptors, Platelet-Derived Growth Factor ; Recombinant Proteins/pharmacology ; Transfection
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  • 79
    Publication Date: 1988-06-10
    Description: Previous studies involving platelet-derived growth factor (PDGF) have been based on the premise that a single cell-surface receptor binds all three isoforms of PDGF (AA, BB, and AB). It is now shown that two populations of PDGF receptor exist and can be distinguished by their ligand binding specificity. The B receptor binds only the BB dimer, whereas the A/B receptor binds AA, BB, and AB dimers. Human dermal fibroblasts appear to express seven times as much B receptor as A/B receptor. The B receptor is responsible for most PDGF receptor phosphorylation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hart, C E -- Forstrom, J W -- Kelly, J D -- Seifert, R A -- Smith, R A -- Ross, R -- Murray, M J -- Bowen-Pope, D F -- DE07063-11/DE/NIDCR NIH HHS/ -- GM35501/GM/NIGMS NIH HHS/ -- HL18645/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1988 Jun 10;240(4858):1529-31.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology, University of Washington, Seattle 98195.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2836952" target="_blank"〉PubMed〈/a〉
    Keywords: Binding, Competitive ; Cell Membrane/metabolism ; Cells, Cultured ; Fibroblasts/metabolism ; Humans ; Kinetics ; Platelet-Derived Growth Factor/*metabolism ; Receptors, Cell Surface/*metabolism ; Receptors, Platelet-Derived Growth Factor ; Skin/*metabolism ; Structure-Activity Relationship
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  • 80
    Publication Date: 1988-06-17
    Description: Forskolin is commonly used to stimulate adenylate cyclase in the study of modulation of ion channels and other proteins by adenosine 3',5'-monophosphate (cAMP)-dependent second messenger systems. In addition to its action on adenylate cyclase, forskolin directly alters the gating of a single class of voltage-dependent potassium channels from a clonal pheochromocytoma (PC12) cell line. This alteration occurred in isolated cell-free patches independent of soluble cytoplasmic enzymes. The effect of forskolin was distinct from those of other agents that raise intracellular cAMP levels. The 1,9-dideoxy derivative of forskolin, which is unable to activate the cyclase, was also effective in altering the potassium channel activity. This direct action of forskolin can lead to misinterpretation of results in experiments in which forskolin is assumed to selectively activate adenylate cyclase.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hoshi, T -- Garber, S S -- Aldrich, R W -- NS07158/NS/NINDS NIH HHS/ -- NS23294/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1988 Jun 17;240(4859):1652-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Neurobiology, Stanford University, School of Medicine, CA 94305.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2454506" target="_blank"〉PubMed〈/a〉
    Keywords: 1-Methyl-3-isobutylxanthine/pharmacology ; Adenylyl Cyclases/*metabolism ; Adrenal Gland Neoplasms/metabolism ; Colforsin/analogs & derivatives/*pharmacology ; Cyclic AMP/metabolism ; Electric Conductivity ; Enzyme Activation/drug effects ; Ion Channels/drug effects/*physiology ; Kinetics ; Pheochromocytoma/metabolism ; Potassium/*metabolism ; Theophylline/pharmacology ; Tumor Cells, Cultured
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  • 81
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1988-09-23
    Description: The kinetics of microtubule reassembly was studied in vitro by quasi-elastic light scattering (QELS). When microtubules assembled in the absence of microtubule-associated proteins (MAPs) were sheared, they rapidly depolymerized, recovered, and reassembled. The mean length of the recovered microtubules was the same as that observed just before shearing, implying that on average one fragment per original microtubule survived the fragmentation and recovery. When microtubules that contained 25 percent brain MAP were sheared, the fragments did not depolymerize extensively and the average length of the fragments decreased by a factor of 3 relative to the unsheared sample. The results support the dynamic instability model, which predicts that cellular microtubules are latently unstable structures protected on their ends by stabilizing caps.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Keates, R A -- Hallett, F R -- New York, N.Y. -- Science. 1988 Sep 23;241(4873):1642-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry and Biochemistry, University of Guelph, Ontario, Canada.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3420415" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Guanosine Diphosphate/physiology ; Guanosine Triphosphate/physiology ; In Vitro Techniques ; Kinetics ; Light ; Microtubule-Associated Proteins/metabolism ; Microtubules/*metabolism ; Scattering, Radiation ; Tubulin/metabolism
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  • 82
    Publication Date: 1988-09-23
    Description: Some strains of human immunodeficiency virus type 1 (HIV-1) can infect primary monocytes and monocyte-derived macrophages in vitro. In this report, the effect of cytokines on the production of one of these strains that shows a tropism for mononuclear phagocytes, designated HIV-1JR-FL, was studied. Primary peripheral blood mononuclear phagocytes infected with HIV-1JR-FL were treated with the hematopoietic factors: granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), macrophage colony-stimulating factor (M-CSF), and gamma-interferon (gamma-IFN). The M-CSF, GM-CSF, IL-3, and gamma-IFN were able to alter HIV-1 production under different conditions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Koyanagi, Y -- O'Brien, W A -- Zhao, J Q -- Golde, D W -- Gasson, J C -- Chen, I S -- New York, N.Y. -- Science. 1988 Sep 23;241(4873):1673-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology and Immunology, UCLA School of Medicine 90024.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3047875" target="_blank"〉PubMed〈/a〉
    Keywords: Biological Products/*pharmacology ; Colony-Stimulating Factors/pharmacology ; Cytokines ; Granulocyte-Macrophage Colony-Stimulating Factor ; Growth Substances/pharmacology ; HIV/*physiology ; Humans ; Interleukin-3/pharmacology ; Kinetics ; Macrophages ; Monocytes/*microbiology ; *Virus Replication
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  • 83
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1987-12-18
    Description: Recordings have been made of changes in intracellular calcium ion concentration ([Ca2+]i) that can be attributed to the operation of an electrogenic, voltage-dependent sodium-calcium (Na-Ca) exchanger in mammalian heart cells. Guinea pig ventricular myocytes under voltage clamp were perfused internally with fura-2, a fluorescent Ca2+-indicator, and changes in [Ca2+]i and membrane current that resulted from Na-Ca exchange were identified through the use of various organic channel blockers and impermeant ions. Depolarization of cells elicited slow increases in [Ca2+]i, with the maximum increase depending on internal [Na+], external [Ca2+], and membrane voltage. Repolarization was associated with net Ca2+ efflux and a decline in the inward current that developed instantaneously upon repolarization. The relation between [Ca2+]i and current was linear, and the slope was made steeper by hyperpolarization.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Barcenas-Ruiz, L -- Beuckelmann, D J -- Wier, W G -- HL29473/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1987 Dec 18;238(4834):1720-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology, University of Maryland School of Medicine, Baltimore.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3686010" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Calcium/*metabolism ; Carrier Proteins/*physiology ; Cell Membrane/physiology ; Guinea Pigs ; Heart/*physiology ; In Vitro Techniques ; Kinetics ; Membrane Potentials ; Sodium-Calcium Exchanger ; Ventricular Function
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  • 84
    Publication Date: 1987-03-20
    Description: Elevation of glucose transport is an alteration common to most virally induced tumors. Rat fibroblasts transformed with wild-type or a temperature-sensitive Fujinami sarcoma virus (FSV) were studied in order to determine the mechanisms underlying the increased transport. Five- to tenfold increases in total cellular glucose transporter protein in response to transformation were accompanied by similar increases in transporter messenger RNA levels. This, in turn, was preceded by an absolute increase in the rate of glucose transporter gene transcription within 30 minutes after shift of the temperature-sensitive FSV-transformed cells to the permissive temperature. The transporter messenger RNA levels in transformed fibroblasts were higher than those found in proliferating cells maintained at the nonpermissive temperature. The activation of transporter gene transcription by transformation represents one of the earliest known effects of oncogenesis on the expression of a gene encoding a protein of well-defined function.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Birnbaum, M J -- Haspel, H C -- Rosen, O M -- AM35430-01/AM/NIADDK NIH HHS/ -- DK 35158/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1987 Mar 20;235(4795):1495-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3029870" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Avian Sarcoma Viruses ; Cell Division ; Cell Line ; *Cell Transformation, Viral ; Fibroblasts ; Gene Expression Regulation ; Kinetics ; Monosaccharide Transport Proteins/*genetics ; RNA, Messenger/genetics ; Rats ; Transcription, Genetic
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  • 85
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1987-11-06
    Description: The c-erbA gene belongs to a multigene family that encodes transcriptional regulatory proteins including the v-erbA oncogene product, steroid hormone receptors, and the vitamin D3 receptor. A v-erbA DNA probe encoding the DNA-binding region of the v-erbA protein was used to screen a human complementary DNA testis library. One of the clones isolated, erbA-T-1, was found to encode a 490-amino acid protein (erbA-T). The erbA-T polypeptide shows high homology with the proteins encoded by both the chicken c-erbA and the human c-erbA-beta genes but is most closely related to the chicken gene. The chicken c-erbA and the human c-erbA-beta genes encode high-affinity receptors for thyroid hormone, and here it is shown that the erbA-T protein binds specifically to 3,5,3'-triiodo-L-thyronine with a dissociation constant of 3.8 +/- 0.2 x 10(-10) M. These data imply that more than one thyroid hormone receptor exists in humans and that these receptors might have different tissue- and gene-activating specificities.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Benbrook, D -- Pfahl, M -- DK-35083/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1987 Nov 6;238(4828):788-91.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Cancer Research Center, La Jolla Cancer Research Foundation, CA 92037.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3672126" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; *Cloning, Molecular ; DNA/*metabolism ; *Genes ; Humans ; Kinetics ; Male ; Protein Biosynthesis ; *Proto-Oncogenes ; Receptors, Thyroid Hormone/*genetics/metabolism ; Testis/*metabolism ; Transcription, Genetic
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  • 86
    Publication Date: 1987-04-03
    Description: Although certain gold [Au(I)] compounds have been used effectively in the treatment of rheumatoid arthritis for some years, the molecular basis for such therapeutic action has been unclear. One possible mechanism of the action of Au(I) compounds is that they protect unsaturated membrane lipids and proteins against oxidative degradation caused by activated phagocytes that are not properly regulated. In this study it has been shown that superoxide ion (O-2.), a product of activated phagocytes, can be oxidized to electronically excited singlet oxygen (O1(2)delta g), an agent that is capable of peroxidation of unsaturated fatty acid derivatives. It has also been shown that antiarthritic Au(I) compounds are effective deactivators of O1(2)delta g with quenching constants on the order of 10(7) M-1 sec-1.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Corey, E J -- Mehrotra, M M -- Khan, A U -- New York, N.Y. -- Science. 1987 Apr 3;236(4797):68-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3563489" target="_blank"〉PubMed〈/a〉
    Keywords: Arthritis, Rheumatoid/drug therapy ; *Auranofin ; Chemistry, Physical ; Humans ; Kinetics ; Lipid Peroxides ; *Oxygen ; Physicochemical Phenomena
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  • 87
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1987-12-18
    Description: The regulatory domain of protein kinase C contains an amino acid sequence between residues 19 and 36 that resembles a substrate phosphorylation site in its distribution of basic residue recognition determinants. The corresponding synthetic peptide (Arg19-Phe-Ala-Arg-Lys-Gly-Ala25-Leu-Arg-Gln-Lys-Asn-Val-His -Glu-Val-Lys-Asn36) acts as a potent substrate antagonist with an inhibitory constant of 147 +/- 9 nM. It is a specific inhibitor of protein kinase C and inhibits both autophosphorylation and protein substrate phosphorylation. Substitution of Ala25 with serine transforms the pseudosubstrate into a potent substrate. These results demonstrate that the conserved region of the regulatory domain (residues 19 to 36) of protein kinase C has the secondary structural features of a pseudosubstrate and may be responsible for maintaining the enzyme in the inactive form in the absence of allosteric activators such as phospholipids.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉House, C -- Kemp, B E -- New York, N.Y. -- Science. 1987 Dec 18;238(4834):1726-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Medicine, University of Melbourne, Repatriation General Hospital, West Heidelberg, Victoria, Australia.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3686012" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Homeostasis ; Kinetics ; Myosin-Light-Chain Kinase/metabolism ; Protein Kinase C/*metabolism ; Substrate Specificity
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  • 88
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1987-12-11
    Description: Vasoactive intestinal peptide (VIP) is a neuropeptide with broad tissue distribution. Although its precise function is unknown, it is thought to exert its effect, at least in part, by interacting with cell surface receptors. Nuclear receptors for VIP have now been identified by specific binding of 125I-labeled VIP to nuclei of a human colonic adenocarcinoma cell line (HT29) and by cross-linking of 125I-labeled VIP to its receptor on intact nuclei. In contrast, 125I-labeled transferrin shows only background binding to nuclei but significant binding to intact cells. Purity of the isolated nuclei was further substantiated by electron microscopy. The apparent molecular sizes of the VIP--cross-linked nuclear and cell surface receptors are similar but not identical.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Omary, M B -- Kagnoff, M F -- DK07202/DK/NIDDK NIH HHS/ -- DK35108/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1987 Dec 11;238(4833):1578-81.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Medicine, 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/2825352" target="_blank"〉PubMed〈/a〉
    Keywords: Adenocarcinoma/*metabolism/ultrastructure ; Cell Line ; Cell Nucleus/*metabolism/ultrastructure ; Colonic Neoplasms/*metabolism/ultrastructure ; Humans ; Kinetics ; Microscopy, Electron ; Receptors, Gastrointestinal Hormone/*metabolism ; Receptors, Vasoactive Intestinal Peptide ; Vasoactive Intestinal Peptide/*metabolism
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  • 89
    Publication Date: 1987-06-05
    Description: The bcl-2 and c-myc proto-oncogenes are brought into juxtaposition with the immunoglobulin heavy chain locus in particular B-cell lymphomas, resulting in high levels of constitutive accumulation of their messenger RNAs. Precisely how the products of the bcl-2 and c-myc genes contribute to tumorigenesis is unknown, but observations that c-myc expression is rapidly induced in nonneoplastic lymphocytes upon stimulation of proliferation raise the possibility that this proto-oncogene is involved in the control of normal cellular growth. In addition to c-myc, the bcl-2 proto-oncogene also was expressed in normal human B and T lymphocytes after stimulation with appropriate mitogens. Comparison of the regulation of the expression of these proto-oncogenes demonstrated marked differences and provided evidence that, in contrast to c-myc, levels of bcl-2 messenger RNA are regulated primarily through transcriptional mechanisms.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Reed, J C -- Tsujimoto, Y -- Alpers, J D -- Croce, C M -- Nowell, P C -- CA-42232/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1987 Jun 5;236(4806):1295-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3495884" target="_blank"〉PubMed〈/a〉
    Keywords: Blood Proteins/biosynthesis/drug effects ; Cycloheximide/pharmacology ; Gene Expression Regulation/*drug effects ; Humans ; Interleukin-2/pharmacology ; Kinetics ; Lymphocyte Activation/*drug effects ; Phytohemagglutinins/pharmacology ; Proto-Oncogenes/*drug effects ; RNA, Messenger/blood/drug effects ; Transcription, Genetic/drug effects
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  • 90
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1987-03-27
    Description: The role of calcium in regulating the contractile state of smooth muscle has been investigated by measuring calcium and contraction in single smooth muscle cells with the calcium-sensitive dye fura-2 and the digital imaging microscope. The concentration of free calcium in the cytoplasm increased after stimulation of the cells by depolarization with high potassium or by application of carbachol. Changes in calcium always preceded contraction. The increase in calcium induced by these stimuli was limited to less than 1 microM. Calcium within the nucleus was also subject to a limitation of its rise during contraction. Intranuclear calcium rose from 200 nM at rest to no more than 300 nM while cytoplasmic calcium rose to over 700 nM. These apparent ceilings for both cytoplasmic and intranuclear calcium may result either from negative feedback of calcium on cytoplasmic and nuclear calcium channel gating mechanisms, respectively, or from the presence of calcium pumps that are strongly activated at the calcium ceilings.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Williams, D A -- Becker, P L -- Fay, F S -- AM07807/AM/NIADDK NIH HHS/ -- HL-14523/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1987 Mar 27;235(4796):1644-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3103219" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Benzofurans ; Bufo marinus ; Calcium/*metabolism ; Carbachol/pharmacology ; Electric Stimulation ; Fura-2 ; Kinetics ; *Muscle Contraction ; Muscle, Smooth/*metabolism ; Potassium/pharmacology ; Software ; Spectrometry, Fluorescence
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 91
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1987-09-25
    Description: An in vitro method has been used to examine whether secretion of renin from the juxtaglomerular apparatus is affected by changes in the sodium chloride concentration of the tubular fluid at the macula densa. Single juxtaglomerular apparatuses were microdissected from rabbits and the tubule segment containing the macula densa was perfused, while simultaneously the entire juxtaglomerular apparatus was superfused, and the fluid was collected for renin measurement. In this preparation, in which influences from renal nerves and local hemodynamic effects are eliminated, a decrease in the tubular sodium chloride concentration at the macula densa results in a prompt stimulation of the renin release rate.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Skott, O -- Briggs, J P -- DK37448/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1987 Sep 25;237(4822):1618-20.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3306925" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Extracellular Space/physiology ; In Vitro Techniques ; Juxtaglomerular Apparatus/cytology/*secretion/ultrastructure ; Kinetics ; Rabbits ; Renin/*secretion ; Sodium Chloride/physiology
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  • 92
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1987-05-22
    Description: Gamma interferon (IFN-gamma) and B cell stimulatory factor-1 (BSF-1), also known as interleukin-4, are T cell-derived lymphokines that have potent effects on B cell proliferation and differentiation. They are often secreted by distinct T cell clones. It is now shown that IFN-gamma stimulates the expression of immunoglobulin (Ig) of the IgG2a isotype and inhibits the production of IgG3, IgG1, IgG2b, and IgE. By contrast, BSF-1 has powerful effects in promoting switching to the expression of IgG1 and IgE but markedly inhibits IgM, IgG3, IgG2a, and IgG2b. These results indicate that BSF-1 and IFN-gamma as well as the T cells that produce them may act as reciprocal regulatory agents in the determination of Ig isotype responses. The effects of IFN-gamma and BSF-1 on isotype expression are independent.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Snapper, C M -- Paul, W E -- New York, N.Y. -- Science. 1987 May 22;236(4804):944-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3107127" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antibodies, Monoclonal ; Antigen-Antibody Complex ; B-Lymphocytes/drug effects/*immunology ; Cricetinae ; Growth Substances/*pharmacology ; Immunoglobulin Isotypes/*biosynthesis ; Interferon-gamma/immunology/*pharmacology ; Interleukin-4 ; Kinetics ; Lymphocyte Activation ; Lymphokines/*pharmacology ; Mice ; Mice, Inbred DBA ; Recombinant Proteins/*pharmacology
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  • 93
    Publication Date: 1987-08-21
    Description: The role of the aspartic acid residue in the serine protease catalytic triad Asp, His, and Ser has been tested by replacing Asp102 of trypsin with Asn by site-directed mutagenesis. The naturally occurring and mutant enzymes were produced in a heterologous expression system, purified to homogeneity, and characterized. At neutral pH the mutant enzyme activity with an ester substrate and with the Ser195-specific reagent diisopropylfluorophosphate is approximately 10(4) times less than that of the unmodified enzyme. In contrast to the dramatic loss in reactivity of Ser195, the mutant trypsin reacts with the His57-specific reagent, tosyl-L-lysine chloromethylketone, only five times less efficiently than the unmodified enzyme. Thus, the ability of His57 to react with this affinity label is not severely compromised. The catalytic activity of the mutant enzyme increases with increasing pH so that at pH 10.2 the kcat is 6 percent that of trypsin. Kinetic analysis of this novel activity suggests this is due in part to participation of either a titratable base or of hydroxide ion in the catalytic mechanism. By demonstrating the importance of the aspartate residue in catalysis, especially at physiological pH, these experiments provide a rationalization for the evolutionary conservation of the catalytic triad.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Craik, C S -- Roczniak, S -- Largman, C -- Rutter, W J -- GM 10765/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1987 Aug 21;237(4817):909-13.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3303334" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Asparagine ; *Aspartic Acid ; Binding Sites ; Catalysis ; *Endopeptidases ; Hydrogen-Ion Concentration ; Kinetics ; Rats ; Serine Endopeptidases ; Structure-Activity Relationship ; Substrate Specificity
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  • 94
    Publication Date: 1987-05-01
    Description: The mechanisms whereby insulin increases diacylglycerol in BC3H-1 myocytes were examined. When [3H]arachidonate labeling of phospholipids was used as an indicator of phospholipase C activation, transient increases in [3H]diacylglycerol were observed between 0.5 and 10 minutes after the onset of insulin treatment. With [3H]glycerol labeling as an indicator of de novo phospholipid synthesis, [3H]diacylglycerol was increased maximally at 1 minute and remained elevated for 20 minutes. [3H]Glycerol-labeled diacylglycerol was largely derived directly from phosphatidic acid. Insulin increased de novo phosphatidic acid synthesis within 5 to 10 seconds; within 1 minute, this synthesis was 60 times greater than that of controls. Thus, the initial increase in diacylglycerol is due to both increased hydrolysis of phospholipids and a burst of de novo phosphatidic acid synthesis. After 5 to 10 minutes, de novo phosphatidic acid synthesis continues as a major source of diacylglycerol. Both phospholipid effects of insulin seem important for generating diacylglycerol and other phospholipid-derived intracellular signaling substances.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Farese, R V -- Konda, T S -- Davis, J S -- Standaert, M L -- Pollet, R J -- Cooper, D R -- AM18608/AM/NIADDK NIH HHS/ -- HD22248/HD/NICHD NIH HHS/ -- New York, N.Y. -- Science. 1987 May 1;236(4801):586-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3107122" target="_blank"〉PubMed〈/a〉
    Keywords: Arachidonic Acid ; Arachidonic Acids/metabolism ; Cell Line ; Diglycerides/*metabolism ; Enzyme Activation ; Glycerides/*metabolism ; Glycerol/metabolism ; Insulin/*pharmacology ; Kinetics ; Muscles/drug effects/*metabolism ; Phosphatidic Acids/*biosynthesis ; Phosphatidylinositols/metabolism ; Phospholipids/metabolism ; Type C Phospholipases/metabolism
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  • 95
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1987-06-05
    Description: Increased levels of intracellular calcium at either pre- or postsynaptic sites are thought to precede changes in synaptic strength. Thus, to induce long-term potentiation in the hippocampus, periods of intense synaptic stimulation would have to transiently raise the levels of cytosolic calcium at postsynaptic sites--dendritic spines in the majority of cases. Since direct experimental verification of this hypothesis is not possible at present, calcium levels have been studied by numerically solving the appropriate electro-diffusion equations for two different postsynaptic structures. Under the assumption that voltage-dependent calcium channels are present on dendritic spines, free intracellular calcium in spines can reach micromolar levels after as few as seven spikes in 20 milliseconds. Moreover, a short, but high-frequency, burst of presynaptic activity is more effective in raising levels of calcium and especially of the calcium-calmodulin complex than sustained low-frequency activity. This behavior is different from that seen at the soma of a typical vertebrate neuron.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gamble, E -- Koch, C -- New York, N.Y. -- Science. 1987 Jun 5;236(4806):1311-5.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3495885" target="_blank"〉PubMed〈/a〉
    Keywords: Action Potentials ; Animals ; Biological Transport, Active ; Calcium/*metabolism ; Cerebral Cortex/physiology ; Dendrites/*metabolism/physiology ; Ganglia, Sympathetic/physiology ; Kinetics ; Membrane Potentials ; Models, Neurological ; Neuronal Plasticity ; Rana catesbeiana ; Synapses/*physiology
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  • 96
    Publication Date: 1987-11-27
    Description: Drosophila heat shock activator protein, a rare transacting factor which is induced upon heat shock to bind specifically to the heat shock regulatory sequence in vivo, has been purified from shocked cells to more than 95 percent homogeneity by sequence-specific duplex oligonucleotide affinity chromatography. The purified protein has a relative molecular mass of 110 kilodaltons, binds to the regulatory sequence with great affinity and specificity, and strongly stimulates transcription of the Drosophila hsp70 gene. Studies with this regulatory protein should lead to an understanding of the biochemical pathway underlying the heat shock phenomenon.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wu, C -- Wilson, S -- Walker, B -- Dawid, I -- Paisley, T -- Zimarino, V -- Ueda, H -- New York, N.Y. -- Science. 1987 Nov 27;238(4831):1247-53.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Biochemistry, National Cancer Institute, Bethesda, MD 20892.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3685975" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Drosophila/*genetics ; *Genes ; *Genes, Regulator ; Heat-Shock Proteins/*genetics ; Kinetics ; Molecular Weight
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  • 97
    Publication Date: 1987-05-08
    Description: In a variety of human genetic diseases, replacement of the absent or defective protein provides significant therapeutic benefits. As a model for a somatic cell gene therapy system, cultured murine fibroblasts were transfected with a human growth hormone (hGH) fusion gene and cells from one of the resulting clonal lines were subsequently implanted into various locations in mice. Such implants synthesized and secreted hGH, which was detectable in the serum. The function of the implants depended on their location and size, and on the histocompatibility of the donor cells with their recipients. The expression of hGH could be modified by addition of regulatory effectors, and, with appropriate immunosuppression, the implants survived for more than 3 months. This approach to gene therapy, here termed "transkaryotic implantation," is potentially applicable to many genetic diseases in that the transfected cell line can be extensively characterized prior to implantation, several anatomical sites are suitable for implantation, and regulated expression of the gene of therapeutic interest can be obtained.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Selden, R F -- Skoskiewicz, M J -- Howie, K B -- Russell, P S -- Goodman, H M -- AM-07055/AM/NIADDK NIH HHS/ -- New York, N.Y. -- Science. 1987 May 8;236(4802):714-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3472348" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cells, Cultured ; DNA, Recombinant ; Fibroblasts/immunology/*transplantation ; *Genetic Engineering ; Graft Survival ; Growth Hormone/biosynthesis/*genetics ; Humans ; Immunosuppression ; Kidney ; Kinetics ; Mice ; Mice, Inbred C3H ; Mice, Inbred C57BL ; Plasmids ; Therapeutics ; Transfection
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  • 98
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1987-06-12
    Description: Computer simulations of the diffusion of a substrate to an enzyme active site were performed. They included the detailed shape of the protein and an accurate description of its electrostatic potential. Application of the method to the diffusion of the superoxide anion to the protein superoxide dismutase revealed that the electric field of the enzyme enhances the association rate of the anion by a factor of 30 or more. Calculated changes in the association rate as a function of ionic strength and amino acid modification paralleled the observed behavior. Design principles of superoxide dismutase are considered with respect to insights provided by the simulations. A possible means of enhancing the enzyme turnover rate through site-directed mutagenesis is proposed.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sharp, K -- Fine, R -- Honig, B -- GM30518/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1987 Jun 12;236(4807):1460-3.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3589666" target="_blank"〉PubMed〈/a〉
    Keywords: *Binding Sites ; *Computer Simulation ; Diffusion ; Enzymes/*metabolism ; Kinetics ; Mathematics ; Mutation ; Superoxide Dismutase/metabolism
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  • 99
    Publication Date: 1987-04-17
    Description: Skeletal muscle ventricles (SMVs) were constructed from canine latissimus dorsi and connected to a totally implantable mock circulation device. The SMVs, stimulated by an implantable pulse generator, pumped continuously for up to 8 weeks in free-running beagle dogs. Systolic pressures produced by the SMVs, initially of 139 +/- 7.2 mmHg and after 1 month of continuous pumping of 107 +/- 7 mmHg, were comparable to normal physiologic pressures in the adult beagles (114 +/- 21 mmHg). After 2 weeks of continuous pumping, the mean stroke work of the SMVs was 0.4 X 10(6) ergs, a performance that compares favorably with the animal's cardiac ventricles. This study shows that canine skeletal muscle which has not received prior training or electrical conditioning can perform sustained work at the high levels needed for an auxiliary cardiovascular pump. It might be possible eventually to use such muscle pumps in humans to assist the failing circulation and to provide support in children with certain types of congenital heart defects.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Acker, M A -- Hammond, R L -- Mannion, J D -- Salmons, S -- Stephenson, L W -- HLBI 34778/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1987 Apr 17;236(4799):324-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2951849" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphatases/metabolism ; Animals ; Blood Circulation ; Blood Pressure ; *Cardiovascular Physiological Phenomena ; Dogs ; Kinetics ; Models, Biological ; Muscles/enzymology/*physiology ; Myosins/metabolism
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  • 100
    Publication Date: 1987-12-18
    Description: Foreign genes can be stably integrated into the genome of a cell by means of DNA-mediated gene transfer techniques, and large quantities of homogenous cells that continuously express these gene products can then be isolated. Such an expression system can be used to study the functional consequences of introducing specific mutations into genes and to study the expressed protein in the absence of cellular components with which it is normally in contact. All four Torpedo acetylcholine receptor (AChR) subunit complementary DNA's were introduced into the genome of a mouse fibroblast cell by DNA-mediated gene transfer. A clonal cell line that stably produced high concentrations of correctly assembled cell surface AChR's and formed proper ligand-gated ion channels was isolated. With this new expression system, recombinant DNA, biochemical, pharmacological, and electrophysiological techniques were combined to study Torpedo AChR's in a single intact system. The physiological and pharmacological profiles of Torpedo AChR's expressed in mouse fibroblast cells differ in some details from those described earlier, and may provide a more accurate reflection of the properties of this receptor in its natural environment.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Claudio, T -- Green, W N -- Hartman, D S -- Hayden, D -- Paulson, H L -- Sigworth, F J -- Sine, S M -- Swedlund, A -- NS 07102/NS/NINDS NIH HHS/ -- NS 21501/NS/NINDS NIH HHS/ -- NS 21714/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1987 Dec 18;238(4834):1688-94.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06510.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3686008" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Line ; Cell Membrane/physiology ; Fibroblasts/metabolism ; *Genes ; Kinetics ; Mice ; Receptors, Cholinergic/*genetics/metabolism ; Torpedo ; *Transfection
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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