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  • 1
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    Two-metal-Ion catalysis in adenylyl cyclase (1999)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1999-07-31
    Description: Adenylyl cyclase (AC) converts adenosine triphosphate (ATP) to cyclic adenosine monophosphate, a ubiquitous second messenger that regulates many cellular functions. Recent structural studies have revealed much about the structure and function of mammalian AC but have not fully defined its active site or catalytic mechanism. Four crystal structures were determined of the catalytic domains of AC in complex with two different ATP analogs and various divalent metal ions. These structures provide a model for the enzyme-substrate complex and conclusively demonstrate that two metal ions bind in the active site. The similarity of the active site of AC to those of DNA polymerases suggests that the enzymes catalyze phosphoryl transfer by the same two-metal-ion mechanism and likely have evolved from a common ancestor.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tesmer, J J -- Sunahara, R K -- Johnson, R A -- Gosselin, G -- Gilman, A G -- Sprang, S R -- DK38828/DK/NIDDK NIH HHS/ -- DK46371/DK/NIDDK NIH HHS/ -- GM34497/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1999 Jul 30;285(5428):756-60.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75235-9050, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10427002" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/metabolism ; Adenylyl Cyclase Inhibitors ; Adenylyl Cyclases/chemistry/genetics/*metabolism ; Animals ; Aspartic Acid/metabolism ; Binding Sites ; Catalysis ; Crystallography, X-Ray ; Deoxyadenine Nucleotides/metabolism/pharmacology ; Dideoxynucleotides ; Dimerization ; Enzyme Inhibitors/metabolism ; Hydrogen Bonding ; Ligands ; Magnesium/*metabolism ; Manganese/*metabolism ; Models, Molecular ; Mutation ; Protein Conformation ; Protein Folding ; Rats ; Thionucleotides/metabolism/pharmacology ; Zinc/*metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
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    Tertiary and quaternary structural changes in Gi alpha 1 induced by GTP hydrolysis (1995)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1995-11-10
    Description: Crystallographic analysis of 2.2 angstrom resolution shows that guanosine triphosphate (GTP) hydrolysis triggers conformational changes in the heterotrimeric G-protein alpha subunit, Gi alpha 1. The switch II and switch III segments become disordered, and linker II connecting the Ras and alpha helical domains moves, thus altering the structures of potential effector and beta gamma binding regions. Contacts between the alpha-helical and Ras domains are weakened, possibly facilitating the release of guanosine diphosphate (GDP). The amino and carboxyl termini, which contain receptor and beta gamma binding determinants, are disordered in the complex with GTP, but are organized into a compact microdomain on GDP hydrolysis. The amino terminus also forms extensive quaternary contacts with neighboring alpha subunits in the lattice, suggesting that multimers of alpha subunits or heterotrimers may play a role in signal transduction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mixon, M B -- Lee, E -- Coleman, D E -- Berghuis, A M -- Gilman, A G -- Sprang, S R -- DK 46371/DK/NIDDK NIH HHS/ -- GM34497/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1995 Nov 10;270(5238):954-60.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235-9050, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7481799" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Crystallography, X-Ray ; GTP-Binding Proteins/*chemistry/metabolism ; Guanosine 5'-O-(3-Thiotriphosphate)/metabolism ; Guanosine Diphosphate/*metabolism ; Guanosine Triphosphate/*metabolism ; Hydrogen Bonding ; Hydrolysis ; Magnesium/metabolism ; Models, Molecular ; *Protein Conformation ; Protein Structure, Secondary ; *Protein Structure, Tertiary
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
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    Structures of active conformations of Gi alpha 1 and the mechanism of GTP hydrolysis (1994)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1994-09-02
    Description: Mechanisms of guanosine triphosphate (GTP) hydrolysis by members of the G protein alpha subunit-p21ras superfamily of guanosine triphosphatases have been studied extensively but have not been well understood. High-resolution x-ray structures of the GTP gamma S and GDP.AlF4- complexes formed by the G protein Gi alpha 1 demonstrate specific roles in transition-state stabilization for two highly conserved residues. Glutamine204 (Gln61 in p21ras) stabilizes and orients the hydrolytic water in the trigonal-bipyramidal transition state. Arginine 178 stabilizes the negative charge at the equatorial oxygen atoms of the pentacoordinate phosphate intermediate. Conserved only in the G alpha family, this residue may account for the higher hydrolytic rate of G alpha proteins relative to those of the p21ras family members. The fold of Gi alpha 1 differs from that of the homologous Gt alpha subunit in the conformation of a helix-loop sequence located in the alpha-helical domain that is characteristic of these proteins; this site may participate in effector binding. The amino-terminal 33 residues are disordered in GTP gamma S-Gi alpha 1, suggesting a mechanism that may promote release of the beta gamma subunit complex when the alpha subunit is activated by GTP.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Coleman, D E -- Berghuis, A M -- Lee, E -- Linder, M E -- Gilman, A G -- Sprang, S R -- DK 46371/DK/NIDDK NIH HHS/ -- GM34497/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Sep 2;265(5177):1405-12.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Dallas, TX.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8073283" target="_blank"〉PubMed〈/a〉
    Keywords: Aluminum Compounds/metabolism ; Arginine/chemistry ; Binding Sites ; Catalysis ; Computer Graphics ; Crystallography, X-Ray ; Fluorides/metabolism ; GTP-Binding Proteins/*chemistry/metabolism ; Glutamine/chemistry ; Guanosine 5'-O-(3-Thiotriphosphate)/metabolism ; Guanosine Diphosphate/metabolism ; Guanosine Triphosphate/*metabolism ; Helix-Loop-Helix Motifs ; Hydrogen Bonding ; Hydrolysis ; Models, Molecular ; *Protein Conformation ; Protein Structure, Secondary
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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