The sodium/proton exchanger Nhx1p is required for endosomal protein trafficking in the yeast Saccharomyces cerevisiae
The sodium/proton exchanger Nhx1p is required for endosomal protein trafficking in the yeast Saccharomyces cerevisiae
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DOI：
10.1091/mbc.11.12.4277
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发表时间：
2000-12-01
影响因子：
3.3
通讯作者：
Stevens, TH
中科院分区：
文献类型：
--
作者：
Bowers, K;Levi, BP;Stevens, TH
我们发现，液泡蛋白分选基因VPS44与编码钠/质子交换器的基因NHX1相同。酿酒酵母蛋白Nhx1p与哺乳动物NHE家族的钠/质子交换器有很高的同源性。Nhx1p被认为是将钠离子输送到前泡隔室，以换取质子。脉冲追逐实验表明，与新合成的可溶液泡蛋白中的35%类似，羧肽酶Y在nhx1 Delta细胞中被错误分选，并从细胞中分泌，nhx1 Delta细胞在液泡附近的异常结构中积累了晚期高尔基体、前高尔基体和溶酶体标记，晚期高尔基体蛋白被蛋白质降解的速度比野生型细胞更快。我们的结果表明，有效地运输出Me前肺泡间隔需要Nhx1p，并且nhx1 Delta细胞表现出“E类”Vps突变体的表型特征。此外，我们还表明，即使在没有液泡ATPase的情况下，Nhx1p也是蛋白质运输所必需的。我们对Nhx1p的分析首次证明，钠/质子交换蛋白对于正确的蛋白质分选很重要，细胞器内离子平衡可能对酵母的内体功能很重要。
We show that the vacuolar protein sorting gene VPS44 is identical to NHX1, a gene that encodes a sodium/proton exchanger. The Saccharomyces cerevisiae protein Nhx1p shows high homology to mammalian sodium/proton exchangers of the NHE family. Nhx1p is thought to transport sodium ions into the prevacuole compartment in exchange for protons. Pulse-chase experiments show that similar to 35% of the newly synthesized soluble vacuolar protein carboxypeptidase Y is missorted in nhx1 Delta cells, and is secreted from the cell, nhx1 Delta cells accumulate late Golgi, prevacuole, and lysosome markers in an aberrant structure next to the vacuole, and late Golgi proteins are proteolytically cleaved more rapidly than in wild-type cells. Our results show that efficient transport out of Me prevacuolar compartment requires Nhx1p, and that nhx1 Delta cells exhibit phenotypes characteristic of the "class E" group of vps mutants. In addition, we show that Nhx1p is required for protein trafficking even in the absence of the vacuolar ATPase. Our analysis of Nhx1p provides the first evidence that a sodium/proton exchange protein is important for correct protein sorting, and that intraorganellar ion balance may be important for endosomal function in yeast.