Abstract
Polarized secretion requires proper targeting of secretory vesicles to specific sites on the plasma membrane. Here we report that the exocyst complex plays a key role in vesicle targeting. Sec15p, an exocyst component, can associate with secretory vesicles and interact specifically with the rab GTPase, Sec4p, in its GTP-bound form. A chain of protein-protein interactions leads from Sec4p and Sec15p on the vesicle, through various subunits of the exocyst, to Sec3p, which marks the sites of exocytosis on the plasma membrane. Sec4p may control the assembly of the exocyst. The exocyst may therefore function as a rab effector system for targeted secretion.
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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Cell Membrane / metabolism
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Centrifugation, Density Gradient
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Cytoplasmic Granules / metabolism*
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Exocytosis
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Fungal Proteins / metabolism*
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GTP-Binding Proteins / metabolism*
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Microscopy, Immunoelectron
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Mutation
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Precipitin Tests
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Protein Binding
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Saccharomyces cerevisiae / metabolism*
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Saccharomyces cerevisiae Proteins*
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Vesicular Transport Proteins
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rab GTP-Binding Proteins*
Substances
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Fungal Proteins
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SEC10 protein, S cerevisiae
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SEC15 protein, S cerevisiae
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SEC3 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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Vesicular Transport Proteins
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GTP-Binding Proteins
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SEC4 protein, S cerevisiae
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rab GTP-Binding Proteins