2eqb
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(New page: 200px<br /><applet load="2eqb" size="450" color="white" frame="true" align="right" spinBox="true" caption="2eqb, resolution 2.70Å" /> '''Crystal structure of...)
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Revision as of 07:58, 21 November 2007
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Crystal structure of the Rab GTPase Sec4p, the Sec2p GEF domain, and phosphate complex
Overview
Vesicular transport during exocytosis is regulated by Rab GTPase (Sec4p in, yeast), which is activated by a guanine nucleotide exchange factor (GEF), called Sec2p. Here, we report the crystal structure of the Sec2p GEF, domain in a complex with the nucleotide-free Sec4p at 2.7 A resolution., Upon complex formation, the Sec2p helices approach each other, flipping, the side chain of Phe-109 toward Leu-104 and Leu-108 of Sec2p. These three, residues provide a hydrophobic platform to attract the side chains of, Phe-49, Ile-53, and Ile-55 in the switch I region as well as Phe-57 and, Trp-74 in the interswitch region of Sec4p. Consequently, the switch I and, II regions are largely deformed, to create a flat hydrophobic interface, that snugly fits the surface of the Sec2p coiled coil. These drastic, conformational changes disrupt the interactions between switch I and the, bound guanine nucleotide, which facilitates the GDP release. Unlike the, recently reported 3.3 A structure of the Sec4p.Sec2p complex, our, structure contains a phosphate ion bound to the P-loop, which may, represent an intermediate state of the nucleotide exchange reaction.
About this Structure
2EQB is a Protein complex structure of sequences from Saccharomyces cerevisiae with PO4 as ligand. Full crystallographic information is available from OCA.
Reference
Crystal structure of the Sec4p{middle dot}Sec2p complex in the nucleotide exchanging intermediate state., Sato Y, Fukai S, Ishitani R, Nureki O, Proc Natl Acad Sci U S A. 2007 May 15;104(20):8305-10. Epub 2007 May 8. PMID:17488829
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