Display Settings:

Format

Send to:

Choose Destination
See comment in PubMed Commons below
Mol Biol Cell. 2006 Jun;17(6):2757-69. Epub 2006 Apr 12.

The rab exchange factor Sec2p reversibly associates with the exocyst.

Author information

  • 1Department 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.

PMID:
16611746
[PubMed - indexed for MEDLINE]
PMCID:
PMC1474791
Free PMC Article

Images from this publication.See all images (9)Free text

Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Write to the Help Desk