title: Concentration of GPI-anchored proteins upon ER exit in yeast.
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.
authors.affiliation: Department of Biochemistry, University of Geneva, Sciences II, 30 quai Ernest Ansermet, CH-1211 Geneva, Switzerland.
authors.forename: Guillaume A
authors.initials: GA
authors.lastname: Castillon
authors.forename: Reika
authors.initials: R
authors.lastname: Watanabe
authors.forename: Marcia
authors.initials: M
authors.lastname: Taylor
authors.forename: Tatjana M E
authors.initials: TM
authors.lastname: Schwabe
authors.forename: Howard
authors.initials: H
authors.lastname: Riezman
mesh_terms: D026905:Amino Acid Transport Systems / Q000235:genetics / Q000378:metabolism; D002473:Cell Wall / Q000235:genetics / Q000378:metabolism*; D022162:Cytoplasmic Vesicles / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D051246:Glucose Transport Proteins, Facilitative; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013696:Temperature; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D026905:Amino Acid Transport Systems; C105281:CCW14 protein, S cerevisiae; C093811:CWP2 protein, S cerevisiae; C093262:EMP24 protein, S cerevisiae; C493590:Erv14 protein, S cerevisiae; C491145:GAP1 protein, S cerevisiae; D051246:Glucose Transport Proteins, Facilitative; D017261:Glycosylphosphatidylinositols; C090594:HXT1 protein, S cerevisiae; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins