Mammalian cells express two VPS4 proteins both of which are involved in intracellular protein trafficking.
Mammalian cells express two VPS4 proteins both of which are involved in intracellular protein trafficking.
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DOI：
10.1006/jmbi.2001.4917
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发表时间：
2001-09
影响因子：
5.6
通讯作者：
S. Scheuring;R. A. Röhricht;B. Schöning-Burkhardt;A. Beyer;S. Müller;H. Abts;K. Köhrer
中科院分区：
文献类型：
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作者：
S. Scheuring;R. A. Röhricht;B. Schöning-Burkhardt;A. Beyer;S. Müller;H. Abts;K. Köhrer
酵母Vps 4蛋白（Vps 4p）是AAA蛋白家族（与多种细胞活性相关的ATP酶）的成员，并且是将蛋白质运输出前液泡内体区室的关键参与者。在人类细胞中，我们鉴定了酵母Vps 4 p的两种非等位基因正向同源蛋白（VPS 4-A和VPS 4-B）。人VPS 4-A和VPS 4-B蛋白彼此之间（80%）和与酵母VPS 4蛋白（分别为59%和60%）显示出高度的序列同一性。缺乏功能性VPS 4基因的酵母细胞表现出温度敏感性生长缺陷，并将羧肽酶Y-转化酶融合蛋白错误定位于细胞表面。人VPS 4基因在vPS 4突变酵母菌株中的异源表达，在人VPS 4-A的情况下，导致对温度敏感性生长缺陷的部分抑制，在人VPS 4-B的情况下，导致对温度敏感性生长缺陷的完全抑制。vps 4突变体酵母细胞的空泡蛋白分选缺陷完全由异源表达的人VPS 4-B蛋白补充，并且部分由人VPS 4-A蛋白补充。突变的人VPS 4-A（E228 Q）和VPS 4-B（E235 Q）蛋白的表达，在其AAA结构域中具有单个氨基酸交换，在两种情况下诱导野生型酵母细胞中的显性负空泡蛋白分选缺陷。双杂交实验表明，人VPS 4-A和VPS 4-B蛋白可以形成异聚复合物，亚细胞定位实验表明，两种人VPS 4蛋白与酵母中的内体区室相关。基于这些结果，我们得出结论，这两种人VPS 4蛋白参与细胞内蛋白质运输，推测在后期内体蛋白质运输步骤，类似于酵母中的Vps 4p。
The yeast Vps4 protein (Vps4p) is a member of the AAA protein family (ATPases associated with diverse cellular activities) and a key player in the transport of proteins out of a prevacuolar endosomal compartment. In human cells, we identified two non-allelic orthologous proteins (VPS4-A and VPS4-B) of yeast Vps4p. The human VPS4-A and VPS4-B proteins display a high degree of sequence identity to each other (80 %) and to the yeast Vps4 protein (59 and 60 %, respectively). Yeast cells lacking a functional VPS4 gene exhibit a temperature-sensitive growth defect and mislocalise a carboxypeptidase Y-invertase fusion protein to the cell surface. Heterologous expression of human VPS4 genes in vps4 mutant yeast strains led, in the case of human VPS4-A, to a partial and, in the case of human VPS4-B, to a complete suppression of the temperature-sensitive growth defect. The vacuolar protein sorting defect of vps4 mutant yeast cells was complemented completely by heterologous expressed human VPS4-B protein, and partially by the human VPS4-A protein. Expression of mutant human VPS4-A (E228Q) and VPS4-B (E235Q) proteins, harbouring single amino acid exchanges in their AAA domains, induced dominant-negative vacuolar protein sorting defects in wild-type yeast cells in both cases. Two-hybrid experiments suggest that the human VPS4-A and VPS4-B proteins can form heteromeric complexes, and subcellular localisation experiments indicate that both human VPS4 proteins associate with endosomal compartments in yeast. Based on these results, we conclude that both human VPS4 proteins are involved in intracellular protein trafficking, presumably at a late endosomal protein transport step, similar to the Vps4p in yeast.