Ubiquitin-mediated targeting of a mutant plasma membrane ATPase, Pma1-7, to the endosomal/vacuolar system in yeast
Ubiquitin-mediated targeting of a mutant plasma membrane ATPase, Pma1-7, to the endosomal/vacuolar system in yeast
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DOI：
10.1091/mbc.e03-10-0727
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发表时间：
2004-05-01
影响因子：
3.3
通讯作者：
Chang, A
中科院分区：
文献类型：
--
作者：
Pizzirusso, M;Chang, A
Pma 1 -7是一种突变的质膜ATP酶，在37 ℃时靶向细胞表面的能力受损，而是被递送到内体/空泡途径进行降解。我们已经提出，Pma 1 -7是一个基于高尔基体的质量控制机制的基板。与野生型Pma 1相比，Pma 1 -7是泛素化的。Pma 1 -7的泛素化和内体靶向依赖于Rsp 5-Bul 1-Bul 2泛素连接酶蛋白复合物，而不是跨膜泛素连接酶Tul 1。Pma 1 -7泛素化的突变体中的蛋白质转运阻断在分泌途径的各个步骤的分析表明，泛素化发生后，ER退出，但在进入内体。在rsp 5 -1细胞中不存在泛素化的情况下，Pma 1 -7被递送到细胞表面并保持稳定。然而，Pma 1 -7仍然受损与洗涤剂不溶性糖脂富集复合物在rsp 5 -1细胞，这表明泛素化是不是Pma 1 -7排除筏的原因。在vps 1细胞中，蛋白质转运到内体途径被阻断，Pma 1 -7被路由到细胞表面。到达vps 1细胞质膜后，Pma 1 -7保持稳定，其泛素化消失，表明在细胞表面具有去泛素化活性。我们认为，Pma 1 -7的排序和命运的调控泛素化。
Pma1-7 is a mutant plasma membrane ATPase that is impaired in targeting to the cell surface at 37degreesC and is delivered instead to the endosomal/vacuolar pathway for degradation. We have proposed that Pma1-7 is a substrate for a Golgi-based quality control mechanism. By contrast with wild-type Pma1, Pma1-7 is ubiquitinated. Ubiquitination and endosomal targeting of Pma1-7 is dependent on the Rsp5-Bul1-Bul2 ubiquitin ligase protein complex but not the transmembrane ubiquitin ligase Tul1. Analysis of Pma1-7 ubiquitination in mutants blocked in protein transport at various steps of the secretory pathway suggests that ubiquitination occurs after ER exit but before endosomal entry. In the absence of ubiquitination in rsp5-1 cells, Pma1-7 is delivered to the cell surface and remains stable. Nevertheless, Pma1-7 remains impaired in association with detergent-insoluble glycolipid-enriched complexes in rsp5-1 cells, suggesting that ubiquitination is not the cause of Pma1-7 exclusion from rafts. In vps1 cells in which protein transport into the endosomal pathway is blocked, Pma1-7 is routed to the cell surface. On arrival at the plasma membrane in vps1 cells, Pma1-7 remains stable and its ubiquitination disappears, suggesting deubiquitination activity at the cell surface. We suggest that Pma1-7 sorting and fate are regulated by ubiquitination.