1gil
From Proteopedia
(New page: 200px<br /><applet load="1gil" size="450" color="white" frame="true" align="right" spinBox="true" caption="1gil, resolution 2.3Å" /> '''STRUCTURE OF ACTIVE C...) |
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| - | [[Image:1gil.jpg|left|200px]]<br /><applet load="1gil" size=" | + | [[Image:1gil.jpg|left|200px]]<br /><applet load="1gil" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1gil, resolution 2.3Å" /> | caption="1gil, resolution 2.3Å" /> | ||
'''STRUCTURE OF ACTIVE CONFORMATIONS OF GIA1 AND THE MECHANISM OF GTP HYDROLYSIS'''<br /> | '''STRUCTURE OF ACTIVE CONFORMATIONS OF GIA1 AND THE MECHANISM OF GTP HYDROLYSIS'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Mechanisms of guanosine triphosphate (GTP) hydrolysis by members of the G | + | 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. |
==About this Structure== | ==About this Structure== | ||
| - | 1GIL is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Rattus_norvegicus Rattus norvegicus] with MG and GSP as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | + | 1GIL is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Rattus_norvegicus Rattus norvegicus] with <scene name='pdbligand=MG:'>MG</scene> and <scene name='pdbligand=GSP:'>GSP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1GIL OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Rattus norvegicus]] | [[Category: Rattus norvegicus]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Berghuis, A | + | [[Category: Berghuis, A M.]] |
| - | [[Category: Coleman, D | + | [[Category: Coleman, D E.]] |
| - | [[Category: Sprang, S | + | [[Category: Sprang, S R.]] |
[[Category: GSP]] | [[Category: GSP]] | ||
[[Category: MG]] | [[Category: MG]] | ||
[[Category: gtp-binding protein]] | [[Category: gtp-binding protein]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:50:27 2008'' |
Revision as of 10:50, 21 February 2008
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STRUCTURE OF ACTIVE CONFORMATIONS OF GIA1 AND THE MECHANISM OF GTP HYDROLYSIS
Overview
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.
About this Structure
1GIL is a Single protein structure of sequence from Rattus norvegicus with and as ligands. Full crystallographic information is available from OCA.
Reference
Structures of active conformations of Gi alpha 1 and the mechanism of GTP hydrolysis., Coleman DE, Berghuis AM, Lee E, Linder ME, Gilman AG, Sprang SR, Science. 1994 Sep 2;265(5177):1405-12. PMID:8073283
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