title: Roles for the Drs2p-Cdc50p complex in protein transport and phosphatidylserine asymmetry of the yeast plasma membrane.
abstract: Drs2p, a P-type adenosine triphosphatase required for a phosphatidylserine (PS) flippase activity in the yeast trans Golgi network (TGN), was first implicated in protein trafficking by a screen for mutations synthetically lethal with arf1 (swa). Here, we show that SWA4 is allelic to CDC50, encoding a membrane protein previously shown to chaperone Drs2p from the endoplasmic reticulum to the Golgi complex. We find that cdc50Delta exhibits the same clathrin-deficient phenotypes as drs2Delta, including delayed transport of carboxypeptidase Y to the vacuole, mislocalization of resident TGN enzymes and the accumulation of aberrant membrane structures. These trafficking defects precede appearance of cell polarity defects in cdc50Delta, suggesting that the latter are a secondary consequence of disrupting Golgi function. Involvement of Drs2p-Cdc50p in PS translocation suggests a role in restricting PS to the cytosolic leaflet of the Golgi and plasma membrane. Annexin V binding and papuamide B hypersensitivity indicate that drs2Delta or cdc50Delta causes a loss of plasma membrane PS asymmetry. However, clathrin and other endocytosis null mutants also exhibit a comparable loss of PS asymmetry, and studies with drs2-ts and clathrin (chc1-ts) conditional mutants suggest that loss of plasma membrane asymmetry is a secondary consequence of disrupting protein trafficking.
authors.affiliation: Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA.
authors.forename: Sophie
authors.initials: S
authors.lastname: Chen
authors.forename: Jiyi
authors.initials: J
authors.lastname: Wang
authors.forename: Baby-Periyanayaki
authors.initials: BP
authors.lastname: Muthusamy
authors.forename: Ke
authors.initials: K
authors.lastname: Liu
authors.forename: Sara
authors.initials: S
authors.lastname: Zare
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: Andersen
authors.forename: Todd R
authors.initials: TR
authors.lastname: Graham
mesh_terms: D000595:Amino Acid Sequence; D017304:Annexin A5 / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002268:Carboxypeptidases / Q000235:genetics / Q000378:metabolism; D043402:Cathepsin A; D002462:Cell Membrane / Q000378:metabolism*; D033922:Clathrin Heavy Chains / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D047630:Depsipeptides / Q000494:pharmacology; D004705:Endocytosis / Q000235:genetics / Q000502:physiology; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006031:Glycosylation; D006056:Golgi Apparatus / Q000378:metabolism; D000072235:Mating Factor; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010455:Peptides / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D010456:Peptides, Cyclic; D010718:Phosphatidylserines / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D043484:Proprotein Convertases / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D021381:Protein Transport / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D017386:Sequence Homology, Amino Acid
chemical_list: D017304:Annexin A5; C427246:CDC50 protein, S cerevisiae; C104014:DRS2 protein, S cerevisiae; D047630:Depsipeptides; D010455:Peptides; D010456:Peptides, Cyclic; D010718:Phosphatidylserines; D010743:Phospholipids; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; C474171:papuamide B; C055996:lanthiopeptin; D033922:Clathrin Heavy Chains; D000072235:Mating Factor; D002268:Carboxypeptidases; D043402:Cathepsin A; C499283:PRC1 protein, S cerevisiae; D043484:Proprotein Convertases; C058751:KEX2 protein, S cerevisiae; D000252:Calcium-Transporting ATPases