Abstract
Here we report the identification of BET3, a new member of a group of interacting genes whose products have been implicated in the targeting and fusion of endoplasmic reticulum (ER) to Golgi transport vesicles with their acceptor compartment. A temperature-sensitive mutant in bet3-1 was isolated in a synthetic lethal screen designed to identify new genes whose products may interact with BET1, a type II integral membrane protein that is required for ER to Golgi transport. At 37 degrees C, bet3-1 fails to transport invertase, alpha-factor, and carboxypeptidase Y from the ER to the Golgi complex. As a consequence, this mutant accumulates dilated ER and small vesicles. The SNARE complex, a docking/fusion complex, fails to form in this mutant. Furthermore, BET3 encodes an essential 22-kDa hydrophilic protein that is conserved in evolution, which is not a component of this complex. These findings support the hypothesis that Bet3p may act before the assembly of the SNARE complex.
Publication types
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Comparative Study
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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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Cloning, Molecular
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Endoplasmic Reticulum / metabolism
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Endoplasmic Reticulum / ultrastructure
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Fungal Proteins / analysis
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Fungal Proteins / biosynthesis
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Fungal Proteins / metabolism*
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Genes, Fungal*
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Golgi Apparatus / metabolism
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Golgi Apparatus / ultrastructure
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Kinetics
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Membrane Proteins / analysis
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Membrane Proteins / biosynthesis
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Membrane Proteins / metabolism*
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Microscopy, Electron
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Molecular Sequence Data
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Recombinant Proteins / biosynthesis
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Recombinant Proteins / metabolism
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Restriction Mapping
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SNARE Proteins
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / physiology*
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Saccharomyces cerevisiae / ultrastructure
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Saccharomyces cerevisiae Proteins*
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Sequence Homology, Amino Acid
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Vesicular Transport Proteins*
Substances
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BET3 protein, S cerevisiae
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Fungal Proteins
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Membrane Proteins
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Recombinant Proteins
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SNARE Proteins
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Saccharomyces cerevisiae Proteins
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Vesicular Transport Proteins