Sec8p and Sec15p are components of a plasma membrane-associated 19.5S particle that may function downstream of Sec4p to control exocytosis

Document Type

Article

Abstract

The SEC8 and SEC15 genes are essential for exocytosis in the yeast Saccharomyces cerevisiae and exhibit strong genetic interactions with SEC4, a gene of the ras superfamily. The SEC8 gene encodes a hydrophilic protein of 122 kD, while the temperature-sensitive sec8-9 allele encodes a protein prematurely truncated at 82 kD by an opal stop codon. The Sec8p sequence contains a 202 amino acid region that is 25% identical to the leucine rich domain of yeast adenylate cyclase that has been implicated in ras responsiveness. Fractionation, stability, and cross-linking studies indicate that Sec8p is a component of a 19.5S particle that also contains Sec15p. This particle is found both in the cytosol and peripherally associated with the plasma membrane, but it is not associated with secretory vesicles. Gel filtration studies suggest that a portion of Sec4p is in association with the Sec8p/Sec15p particle. We propose that this particle may function as a downstream effector of Sec4p, serving to direct the fusion of secretory vesicles with the plasma membrane.

Publication Date

1-1-1992

Publication Title

Journal of Cell Biology

ISSN

00219525

Volume

118

Issue

5

First Page

1041

Last Page

1056

PubMed ID

1512289

Digital Object Identifier (DOI)

10.1083/jcb.118.5.1041

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