The BioGRID | PUBLICATION VIEW

	Mol. Biol. Cell Jun (2006); 17(6):2757-69
The rab exchange factor Sec2p reversibly associates with the exocyst-
Medkova M, France YE, Coleman J, Novick P
Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA-
Abstract: Activation of the rab GTPase, Sec4p, by its exchange factor, Sec2p, is needed for polarized transport of secretory vesicles to exocytic sites and for exocytosis- A small region in the C-terminal half of Sec2p regulates its localization- Loss of this region results in temperature-sensitive growth and the depolarized accumulation of secretory vesicles- Here, we show that Sec2p associates with the exocyst, an octameric effector of Sec4p involved in tethering secretory vesicles to the plasma membrane- Specifically, the exocyst subunit Sec15p directly interacts with Sec2p- This interaction normally occurs on secretory vesicles and serves to couple nucleotide exchange on Sec4p to the recruitment of the Sec4p effector- The mislocalization of Sec2p mutants correlates with dramatically enhanced binding to the exocyst complex- We propose that Sec2p is normally released from the exocyst after vesicle tethering so that it can recycle onto a new round of vesicles- The mislocalization of Sec2p mutants results from a failure to be released from Sec15p, blocking this recycling pathway-
[PUBMED: 16611746]