The Exocyst is a multiprotein complex required for exocytosis in Saccharomyces cerevisiae.
In the yeast Saccharomyces cerevisiae, the products of at least 15 genes are involved specifically in vesicular transport from the Golgi apparatus to the plasma membrane. Previously, we have shown that three of these genes, SEC6, SEC8 and SEC15, encode components of a multisubunit complex which localizes to the tip of the bud, the predominant site of exocytosis in S. cerevisiae. Mutations in three more of these genes, SEC3, SEC5 and SEC10, were found to disrupt the subunit integrity of the Sec6-Sec8-Sec15 complex, indicating that these genes may encode some of the remaining components of this complex. To examine this possibility, we cloned and sequenced the SEC5 and SEC10 genes, disrupted them, and either epitope tagged them (Sec5p) or prepared polyclonal antisera (Sec10p) to them for co-immunoprecipitation studies. Concurrently, we biochemically purified the remaining unidentified polypeptides of the Sec6-Sec8-Sec15 complex for peptide microsequencing. The genes encoding these components were identified by comparison of predicted amino acid sequences with those obtained from peptide microsequencing of the purified complex components. In addition to Sec6p, Sec8p and Sec15p, the complex contains the proteins encoded by SEC3, SEC5, SEC10 and a novel gene, EXO70. Since these seven proteins function together in a complex required for exocytosis, and not other intracellular trafficking steps, we have named it the Exocyst.
TerBush
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Yale University School of Medicine, Department of Cell Biology, New Haven, CT 06520-8002, USA.
Maurice
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Roth
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Novick
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D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans; D002352:Carrier Proteins; D003001:Cloning, Molecular; D005089:Exocytosis; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism; D005800:Genes, Fungal; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011506:Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D033921:Vesicular Transport Proteins
D002352:Carrier Proteins; C103132:EXO70 protein, S cerevisiae; C490685:EXOC3 protein, human; C489607:EXOC4 protein, human; C489222:EXOC6B protein, human; D005656:Fungal Proteins; D011506:Proteins; D011994:Recombinant Proteins; C060862:SEC15 protein, S cerevisiae; C103130:SEC3 protein, S cerevisiae; C103131:SEC5 protein, S cerevisiae; C490684:SEC6 protein, S cerevisiae; C489603:SEC8 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins; D019204:GTP-Binding Proteins