Gerrard S R, Bryant N J, Stevens T H
Institute of Molecular Biology, Department of Chemistry, University of Oregon, Eugene, Oregon 97403-1229, USA.
Mol Biol Cell. 2000 Feb;11(2):613-26. doi: 10.1091/mbc.11.2.613.
Mutations in the VPS (vacuolar protein sorting) genes of Saccharomyces cerevisiae have been used to define the trafficking steps that soluble vacuolar hydrolases take en route from the late Golgi to the vacuole. The class D VPS genes include VPS21, PEP12, and VPS45, which appear to encode components of a membrane fusion complex involved in Golgi-to-endosome transport. Vps21p is a member of the Rab family of small Ras-like GTPases and shows strong homology to the mammalian Rab5 protein, which is involved in endocytosis and the homotypic fusion of early endosomes. Although Rab5 and Vps21p appear homologous at the sequence level, it has not been clear if the functions of these two Rabs are similar. We find that Vps21p is an endosomal protein that is involved in the delivery of vacuolar and endocytosed proteins to the vacuole. Vacuolar and endocytosed proteins accumulate in distinct transport intermediates in cells that lack Vps21p function. Therefore, it appears that Vps21p is involved in two trafficking steps into the prevacuolar/late endosomal compartment.
酿酒酵母液泡蛋白分选（VPS）基因的突变已被用于确定可溶性液泡水解酶从高尔基体晚期到液泡的运输步骤。D类VPS基因包括VPS21、PEP12和VPS45，它们似乎编码参与高尔基体到内体运输的膜融合复合物的组分。Vps21p是小Ras样GTP酶Rab家族的成员，与参与内吞作用和早期内体同型融合的哺乳动物Rab5蛋白具有高度同源性。尽管Rab5和Vps21p在序列水平上看起来同源，但这两种Rab的功能是否相似尚不清楚。我们发现Vps21p是一种内体蛋白，参与将液泡蛋白和内吞蛋白递送至液泡。在缺乏Vps21p功能的细胞中，液泡蛋白和内吞蛋白积聚在不同的运输中间体中。因此，Vps21p似乎参与了进入前液泡/晚期内体区室的两个运输步骤。
