Cdc50p, a protein required for polarized growth, associates with the Drs2p P-type ATPase implicated in phospholipid translocation in Saccharomyces cerevisiae
Cdc50p, a protein required for polarized growth, associates with the Drs2p P-type ATPase implicated in phospholipid translocation in Saccharomyces cerevisiae
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DOI：
10.1091/mbc.e03-11-0829
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发表时间：
2004-07-01
影响因子：
3.3
通讯作者：
Tanaka, K
中科院分区：
文献类型：
--
作者：
Saito, K;Fujimura-Kamada, K;Tanaka, K
CDC50P是酵母细胞极化生长所必需的跨膜蛋白，定位于胞体晚期。遗传学研究表明，CDC50的功能类似于编码氨基磷脂转移酶(APT)亚家族的P型ATPase的DRS2。在低温下，drs2Delta突变细胞表现出皮质肌动蛋白斑块的去极化和极性调节因子，如Bni1p和Gic1p的错误定位，其方式与cdc50Delta突变相似。CDC50p和Drs2p均定位于跨高尔基体网络和晚期内体。从膜蛋白提取物中提取的CDC50p与Drs2p共免疫沉淀。在cdc50Delta突变细胞中，drs2p位于内质网(ER)上，而在drs2Delta细胞中，CDc50p存在于ER膜上，这表明CDc5op-drs2p复合体在ER膜上的结合是将CDc5op-drs2p复合体运输到反高尔基网络所必需的。Lem3/Ros3p是CDC50p的同源物，与另一种APT Dnf1p共沉淀；Dnf1p退出内质网需要Lem3p。CDC50p-Drs2p和Lem3p-Dnf1p在内吞作用被阻断后都被限制在质膜上，这表明这些蛋白在胞外和内吞途径之间循环，可能发挥多余的功能。因此，磷脂的不对称性在细胞极性的建立中起着重要的作用；CDC50p/Lem3p家族可能是APT亚家族中独特的P型ATPase的潜在亚基。
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 Cdc5op-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.