2fmx: Difference between revisions
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'''An open conformation of switch I revealed by Sar1-GDP crystal structure at low Mg(2+)''' | '''An open conformation of switch I revealed by Sar1-GDP crystal structure at low Mg(2+)''' | ||
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[[Category: Rao, Y.]] | [[Category: Rao, Y.]] | ||
[[Category: Yuan, C.]] | [[Category: Yuan, C.]] | ||
[[Category: | [[Category: Cop ii assembly]] | ||
[[Category: | [[Category: Crystal structure]] | ||
[[Category: | [[Category: Dimerization]] | ||
[[Category: | [[Category: Sar1]] | ||
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Revision as of 04:05, 4 May 2008
An open conformation of switch I revealed by Sar1-GDP crystal structure at low Mg(2+)
OverviewOverview
Mg2+ is essential for guanosine triphosphatase activity and plays key roles in guanine nucleotide binding and preserving the structural integrity of GTP-binding proteins. To understand the structural basis for Mg2+ function during the GDP/GTP exchange process, we determined the crystal structure of Delta9-Sar1-GDP at low Mg2+ concentration at 1.8A. Two Sar1-GDP molecules in the crystal form a dimer with Mg2+ presenting only in molecule B but not in molecule A. The absence of Mg2+ induces significant conformational changes in the switch I region in molecule A that shows similarities with those of Ha-Ras bound to Sos. The current structure reveals an important regulatory role for Mg2+. We suggest that guanine nucleotide exchange factor may utilize this feature to generate an open conformation for GDP/GTP exchange. Furthermore, we propose a mechanism for COPII assembly and disassembly in which dimerization of Sar1 plays an important role.
About this StructureAbout this Structure
2FMX is a Single protein structure of sequence from Cricetulus griseus. Full crystallographic information is available from OCA.
ReferenceReference
An open conformation of switch I revealed by Sar1-GDP crystal structure at low Mg2+., Rao Y, Bian C, Yuan C, Li Y, Chen L, Ye X, Huang Z, Huang M, Biochem Biophys Res Commun. 2006 Sep 29;348(3):908-15. Epub 2006 Aug 1. PMID:16899220 Page seeded by OCA on Sun May 4 04:05:04 2008