An endosome-to-plasma membrane pathway involved in trafficking of a mutant plasma membrane ATPase in yeast
An endosome-to-plasma membrane pathway involved in trafficking of a mutant plasma membrane ATPase in yeast
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DOI：
10.1091/mbc.11.2.579
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发表时间：
2000-02-01
影响因子：
3.3
通讯作者：
Chang, A
中科院分区：
文献类型：
--
作者：
Luo, WJ;Chang, A
由 PMA1 编码的质膜 ATP 酶通过分泌途径递送至细胞表面。此前，我们描述了一种温度敏感的 pma2 突变体，其中新合成的 Pma1-7 不会被递送到质膜，而是在 37 摄氏度下错误定位到液泡。一些在液泡蛋白质分选方面存在缺陷的 vps 突变体通过允许突变体 Pma1 再次移动到质膜来抑制靶向缺陷的 pma1。在这项研究中，我们通过监测 vps36、vps1 和 vps8 突变体中 Pma1-7 的运动来分析内体系统中的运输。诱导表达后，突变型 Pma1 在 vps36 细胞的前液泡区室中积聚。追踪后，新合成的 Pma1-7 的一部分被传递到质膜。在 vps1 和 vps8 细胞中，新合成的突变体 Pma1 在到达细胞表面之前均以小点状结构出现。然而，vps8 和 vps1 中的生物合成膜运输似乎遵循不同的路线：液泡蛋白分选受体 Vps10p 在 vps8 中稳定，但在 vps1 中不稳定。此外，通过大容量膜标记 FM 4-64 的内吞作用，在 vps8（和 vps36）中发现了内吞递送到液泡的缺陷，但在 vps2 中没有发现。此外，在 vps8 细胞中，交配受体 Ste3 的细胞表面存在缺陷性下调，这与从内体区室到质膜的持续受体再循环一致。这些数据支持一个模型，其中突变型 Pma1 在 vps1 细胞中从高尔基体转移到表面。我们假设，与 vps1 相比，在 vps8 和 vps36 中，突变体 Pma1 通过内体中间体移动到表面，这表明内体到表面的运输途径。
The plasma membrane ATPase, encoded by PMA1, is delivered to the cell surface via the secretory pathway. Previously, we characterized a temperature-sensitive pma2 mutant in which newly synthesized Pma1-7 is not delivered to the plasma membrane but is mislocalized instead to the vacuole at 37 degrees C. Several vps mutants, which are defective in vacuolar protein sorting, suppress targeting-defective pma1 by allowing mutant Pma1 to move once again to the plasma membrane. Ln this study, we have analyzed trafficking in the endosomal system by monitoring the movement of Pma1-7 in vps36, vps1, and vps8 mutants. Upon induction of expression, mutant Pma1 accumulates in the prevacuolar compartment in vps36 cells. After chase, a fraction of newly synthesized Pma1-7 is delivered to the plasma membrane. In both vps1 and vps8 cells, newly synthesized mutant Pma1 appears in small punctate structures before arrival at the cell surface. Nevertheless, biosynthetic membrane traffic appears to follow different routes in vps8 and vps1: the vacuolar protein-sorting receptor Vps10p is stable in vps8 but not in vps1. Furthermore, a defect in endocytic delivery to the vacuole was revealed in vps8 (and vps36) but not vps2 by endocytosis of the bulk membrane marker FM 4-64. Moreover, in vps8 cells, there is defective down-regulation from the cell surface of the mating receptor Ste3, consistent with persistent receptor recycling from an endosomal compartment to the plasma membrane. These data support a model in which mutant Pma1 is diverted from the Golgi to the surface in vps1 cells. We hypothesize that in vps8 and vps36, in contrast to vps1, mutant Pma1 moves to the surface via endosomal intermediates, implicating an endosome-to-surface traffic pathway.