Abstract
To identify potential Sec4 effectors, we isolated high copy suppressors of a Sec4 effector domain mutant. The most potent of these was found to be SEC9, a gene required for post-Golgi transport. The sole essential domain of Sec9 has significant sequence similarity to the neuronal protein SNAP-25, a component of the SNARE complex, that is implicated in vesicle targeting and fusion. Analogous to SNAP-25, Sec9 is bound to the yeast plasma membrane and is absent from post-Golgi vesicles. Furthermore, Sec9 is physically associated with two proteins that are homologous to components of the neuronal SNARE complex. Our results identify Sec9 as the yeast cognate of SNAP-25 and suggest that SNARE complexes acting at specific stages of vesicular transport serve as the ultimate targets of regulation by members of the Sec4/Ypt1/Rab family of GTPases.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Cell Membrane / metabolism
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Exocytosis*
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Fungal Proteins / genetics
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Fungal Proteins / metabolism
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Fungal Proteins / physiology*
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GTP-Binding Proteins / physiology*
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Membrane Proteins / metabolism
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Membrane Proteins / physiology
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Molecular Sequence Data
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Mutagenesis, Site-Directed
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Nerve Tissue Proteins / metabolism
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Nerve Tissue Proteins / physiology
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Qa-SNARE Proteins
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Qc-SNARE Proteins
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R-SNARE Proteins
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Saccharomyces cerevisiae
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Saccharomyces cerevisiae Proteins*
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Structure-Activity Relationship
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Synaptosomal-Associated Protein 25
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rab GTP-Binding Proteins*
Substances
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Fungal Proteins
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Membrane Proteins
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Nerve Tissue Proteins
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Qa-SNARE Proteins
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Qc-SNARE Proteins
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R-SNARE Proteins
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SEC9 protein, S cerevisiae
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SSO1 protein, S cerevisiae
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SSO2 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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Synaptosomal-Associated Protein 25
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GTP-Binding Proteins
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SEC4 protein, S cerevisiae
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rab GTP-Binding Proteins
Associated data
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GENBANK/L14710
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GENBANK/L34336
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SWISSPROT/P34492