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| {{STRUCTURE_2eqb| PDB=2eqb | SCENE= }} | | {{STRUCTURE_2eqb| PDB=2eqb | SCENE= }} |
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| '''Crystal structure of the Rab GTPase Sec4p, the Sec2p GEF domain, and phosphate complex'''
| | ===Crystal structure of the Rab GTPase Sec4p, the Sec2p GEF domain, and phosphate complex=== |
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| ==Overview==
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| 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.
| | The line below this paragraph, {{ABSTRACT_PUBMED_17488829}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 17488829 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_17488829}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Sato, Y.]] | | [[Category: Sato, Y.]] |
| [[Category: Coiled coil]] | | [[Category: Coiled coil]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 02:59:23 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 14:44:05 2008'' |
