2eqb

<StructureSection load='2eqb' size='340' side='right' caption='[[2eqb]], [[Resolution|resolution]] 2.70&Aring;' scene=''>

<table><tr><td colspan='2'>[[2eqb]] is a 3 chain structure with sequence from [http://en.wikipedia.org/wiki/Atcc_18824 Atcc 18824]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2EQB OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=2EQB FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=PO4:PHOSPHATE+ION'>PO4</scene></td></tr>

<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[2e7s|2e7s]], [[2ocy|2ocy]]</td></tr>

<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=2eqb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2eqb OCA], [http://pdbe.org/2eqb PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=2eqb RCSB], [http://www.ebi.ac.uk/pdbsum/2eqb PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=2eqb ProSAT]</span></td></tr>

[[http://www.uniprot.org/uniprot/SEC4_YEAST SEC4_YEAST]] Involved in exocytosis. Maybe by regulating the binding and fusion of secretory vesicles with the cell surface. The GTP-bound form of SEC4 may interact with an effector, thereby stimulating its activity and leading to exocytotic fusion. SEC4 may be an upstream activator of the 19.5S SEC8/SEC15 particle. SEC4 probably interacts directly with SEC8; it could serve as the attachment site for the SEC8/SEC15 particle.<ref>PMID:16390997</ref> [[http://www.uniprot.org/uniprot/SEC2_YEAST SEC2_YEAST]] Guanine nucleotide exchange factor for SEC4, catalyzing the dissociation of GDP from SEC4 and also potently promoting binding of GTP. Activation of SEC4 by SEC2 is needed for the directed transport of vesicles to sites of exocytosis. Binds the Rab GTPase YPT32, but does not have exhange activity on YPT32.<ref>PMID:9199166</ref> <ref>PMID:10747090</ref> <ref>PMID:12045183</ref>

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== Publication Abstract from PubMed ==

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.

Crystal structure of the Sec4p.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<ref>PMID:17488829</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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<div class="pdbe-citations 2eqb" style="background-color:#fffaf0;"></div>

[[Category: Atcc 18824]]

[[Category: Fukai, S]]

[[Category: Ishitani, R]]

[[Category: Nureki, O]]

[[Category: Sato, Y]]

[[Category: Endocytosis-exocytosis complex]]