Abstract
Delivery of cytoplasmic vesicles to discrete plasma-membrane domains is critical for establishing and maintaining cell polarity, neurite differentiation and regulated exocytosis. The exocyst is a multisubunit complex required for vectorial targeting of a subset of secretory vesicles. Mechanisms that regulate the activity of this complex in mammals are unknown. Here we show that Sec5, an integral component of the exocyst, is a direct target for activated Ral GTPases. Ral GTPases regulate targeting of basolateral proteins in epithelial cells, secretagogue-dependent exocytosis in neuroendocrine cells and assembly of exocyst complexes. These observations define Ral GTPases as critical regulators of vesicle trafficking.
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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Animals
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Caco-2 Cells
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Carrier Proteins / physiology
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Cell Polarity / physiology
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Exocytosis / physiology*
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Fungal Proteins / physiology
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GTPase-Activating Proteins*
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HeLa Cells
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Humans
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Membrane Proteins / physiology*
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PC12 Cells
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Phospholipase D / physiology
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Protein Transport / physiology
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Rats
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Secretory Vesicles / physiology
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Signal Transduction*
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Vesicular Transport Proteins
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ral GTP-Binding Proteins / physiology*
Substances
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Carrier Proteins
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Exoc2 protein, rat
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Fungal Proteins
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GTPase-Activating Proteins
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Membrane Proteins
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Ralbp1 protein, rat
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Vesicular Transport Proteins
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Phospholipase D
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phospholipase D1
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ral GTP-Binding Proteins