Abstract
Exocytosis in yeast occurs at plasma membrane subdomains whose locations vary with the cell cycle, but the primary protein determinants of these sites are unknown. A functional fusion of Sec3 protein with green fluorescent protein (Sec3-GFP) localizes to the site of polarized exocytosis for each cell-cycle stage, where it colocalizes with Sec4p and Sec8p. Sec3-GFP localization is independent of secretory pathway function, of the actin and septin cytoskeletons, and of the polarity establishment proteins. We propose that Sec3p is a spatial landmark defining sites of exocytosis. Polarized secretion would result from the coupling of actin-dependent vesicle targeting with Sec3p-dependent establishment of the vesicle fusion site.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Actins / analysis
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Actins / metabolism
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Carrier Proteins*
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Cell Cycle Proteins / analysis
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Cell Cycle Proteins / genetics
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Cell Polarity / physiology*
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Cytoskeletal Proteins*
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Cytoskeleton / chemistry
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Cytoskeleton / metabolism
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Exocytosis / physiology*
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Fungal Proteins / analysis
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Fungal Proteins / metabolism*
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GTP Phosphohydrolases
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GTP-Binding Proteins / analysis
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Green Fluorescent Proteins
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Indicators and Reagents
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Intracellular Membranes / physiology
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Luminescent Proteins
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Membrane Proteins
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Mutation
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Profilins
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Proteins / analysis
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Saccharomyces cerevisiae / chemistry
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Saccharomyces cerevisiae / cytology
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Saccharomyces cerevisiae / metabolism*
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Saccharomyces cerevisiae Proteins*
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Schizosaccharomyces pombe Proteins
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Transcription Factors / analysis
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Vesicular Transport Proteins
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rab GTP-Binding Proteins*
Substances
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Actins
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CDC12 protein, S cerevisiae
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CDC3 protein, S cerevisiae
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Carrier Proteins
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Cell Cycle Proteins
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Cytoskeletal Proteins
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Fungal Proteins
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Indicators and Reagents
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Luminescent Proteins
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Membrane Proteins
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Profilins
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Proteins
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SEC3 protein, S cerevisiae
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SEC8 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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Schizosaccharomyces pombe Proteins
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Transcription Factors
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Vesicular Transport Proteins
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cdc10 protein, S pombe
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Green Fluorescent Proteins
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CDC10 protein, S cerevisiae
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GTP Phosphohydrolases
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GTP-Binding Proteins
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SEC4 protein, S cerevisiae
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rab GTP-Binding Proteins