Abstract
Previous biochemical work has revealed two parallel routes of exit from the endoplasmic reticulum (ER) in the yeast Saccharomyces cerevisiae, one seemingly specific for glycosyl-phosphatidylinositol (GPI)-anchored proteins. Using the coat protein II (COPII) mutant sec31-1, we visualized ER exit sites (ERES) and identified three distinct ERES populations in vivo. One contains glycosylated pro-alpha-factor, the second contains the GPI-anchored proteins Cwp2p, Ccw14p and Tos6p and the third is enriched with the hexose transporter, Hxt1p. Concentration of GPI-anchored proteins prior to budding requires anchor remodeling, and Hxt1p incorporation into ERES requires the COPII components Sec12p and Sec16p. Additionally, we have found that GPI-anchored protein ER exit is controlled by the p24 family member Emp24p, whereas ER export of most transmembrane proteins requires the Cornichon homologue Erv14p.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Transport Systems / genetics
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Amino Acid Transport Systems / metabolism
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Cell Wall / genetics
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Cell Wall / metabolism*
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Cytoplasmic Vesicles / metabolism
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Endoplasmic Reticulum / metabolism*
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Glucose Transport Proteins, Facilitative
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Glycosylphosphatidylinositols / metabolism*
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Membrane Glycoproteins / genetics
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Membrane Glycoproteins / metabolism*
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Membrane Proteins / genetics
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Membrane Proteins / metabolism
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Monosaccharide Transport Proteins / genetics
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Monosaccharide Transport Proteins / metabolism
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism*
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism*
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Temperature
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Vesicular Transport Proteins / genetics
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Vesicular Transport Proteins / metabolism
Substances
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Amino Acid Transport Systems
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CCW14 protein, S cerevisiae
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CWP2 protein, S cerevisiae
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EMP24 protein, S cerevisiae
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Erv14 protein, S cerevisiae
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GAP1 protein, S cerevisiae
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Glucose Transport Proteins, Facilitative
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Glycosylphosphatidylinositols
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HXT1 protein, S cerevisiae
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Membrane Glycoproteins
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Membrane Proteins
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Monosaccharide Transport Proteins
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Saccharomyces cerevisiae Proteins
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Vesicular Transport Proteins