title: Cdc50p, a protein required for polarized growth, associates with the Drs2p P-type ATPase implicated in phospholipid translocation in Saccharomyces cerevisiae.
abstract: Cdc50p, a transmembrane protein localized to the late endosome, is required for polarized cell growth in yeast. Genetic studies suggest that CDC50 performs a function similar to DRS2, which encodes a P-type ATPase of the aminophospholipid translocase (APT) subfamily. At low temperatures, drs2Delta mutant cells exhibited depolarization of cortical actin patches and mislocalization of polarity regulators, such as Bni1p and Gic1p, in a manner similar to the cdc50Delta mutant. Both Cdc50p and Drs2p were localized to the trans-Golgi network and late endosome. Cdc50p was coimmunoprecipitated with Drs2p from membrane protein extracts. In cdc50Delta mutant cells, Drs2p resided on the endoplasmic reticulum (ER), whereas Cdc50p was found on the ER membrane in drs2Delta cells, suggesting that the association on the ER membrane is required for transport of the Cdc50p-Drs2p complex to the trans-Golgi network. Lem3/Ros3p, a homolog of Cdc50p, was coimmunoprecipitated with another APT, Dnf1p; Lem3p was required for exit of Dnf1p out of the ER. Both Cdc50p-Drs2p and Lem3p-Dnf1p were confined to the plasma membrane upon blockade of endocytosis, suggesting that these proteins cycle between the exocytic and endocytic pathways, likely performing redundant functions. Thus, phospholipid asymmetry plays an important role in the establishment of cell polarity; the Cdc50p/Lem3p family likely constitute potential subunits specific to unique P-type ATPases of the APT subfamily.
authors.affiliation: Division of Molecular Interaction, Institute for Genetic Medicine, Hokkaido University Graduate School of Medicine, Sapporo 060-0815, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Saito
authors.forename: Konomi
authors.initials: K
authors.lastname: Fujimura-Kamada
authors.forename: Nobumichi
authors.initials: N
authors.lastname: Furuta
authors.forename: Utako
authors.initials: U
authors.lastname: Kato
authors.forename: Masato
authors.initials: M
authors.lastname: Umeda
authors.forename: Kazuma
authors.initials: K
authors.lastname: Tanaka
mesh_terms: D018528:ATP-Binding Cassette Transporters; D048868:Adaptor Proteins, Signal Transducing; D000251:Adenosine Triphosphatases / Q000032:analysis / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000032:analysis / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D016764:Cell Polarity; D011992:Endosomes / Q000737:chemistry / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics; D026901:Membrane Transport Proteins / Q000032:analysis / Q000378:metabolism; D008840:Microfilament Proteins / Q000032:analysis / Q000378:metabolism; D049294:Phospholipid Transfer Proteins; D010743:Phospholipids / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D017384:Sequence Deletion / Q000235:genetics; D021601:trans-Golgi Network / Q000737:chemistry / Q000378:metabolism
chemical_list: D018528:ATP-Binding Cassette Transporters; D048868:Adaptor Proteins, Signal Transducing; C105191:Bni1 protein, S cerevisiae; C427246:CDC50 protein, S cerevisiae; D002352:Carrier Proteins; C104014:DRS2 protein, S cerevisiae; C109252:GIC1 protein, S cerevisiae; C478771:Lem3 protein, S cerevisiae; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D008840:Microfilament Proteins; D049294:Phospholipid Transfer Proteins; D010743:Phospholipids; D029701:Saccharomyces cerevisiae Proteins; D000251:Adenosine Triphosphatases; D000252:Calcium-Transporting ATPases; C480601:Dnf1 protein, S cerevisiae; C104013:NEO1 protein, S cerevisiae