Armstrong J, Craighead M W, Watson R, Ponnambalam S, Bowden S
School of Biological Sciences, University of Sussex, Falmer, Brighton, England.
Mol Biol Cell. 1993 Jun;4(6):583-92. doi: 10.1091/mbc.4.6.583.
The ypt/rab proteins are a family of small GTP-binding proteins thought to be required for different stages of membrane traffic. From the fission yeast Schizosaccharomyces pombe we have isolated and characterized ypt5, a gene encoding a homologue of rab5, a mammalian protein apparently involved in regulating fusion of early endosomes. Recombinant ypt5 protein bound GTP. The ypt5 gene was found to be essential for viability on minimal media, but ypt5-disrupted cells grew slowly on some rich media and accumulated a population of small vesicles not observed in wild-type cells. Canine rab5 cDNA could replace the ypt5 gene in S. pombe and restore normal growth and viability. Ypt5 protein expressed in mammalian cells colocalized with the transferrin receptor to early endosomes. Thus, molecular aspects of the early endocytic pathway may be conserved between mammalian cells and S. pombe and hence may be amenable to genetic analysis.
Ypt/Rab蛋白是一类小GTP结合蛋白，被认为在膜运输的不同阶段发挥作用。我们从裂殖酵母粟酒裂殖酵母中分离并鉴定了ypt5，该基因编码rab5的同源物，rab5是一种哺乳动物蛋白，显然参与早期内体融合的调控。重组ypt5蛋白结合GTP。发现ypt5基因对于在基本培养基上的生存能力至关重要，但ypt5基因缺失的细胞在一些丰富培养基上生长缓慢，并积累了一群在野生型细胞中未观察到的小泡。犬rab5 cDNA可以替代粟酒裂殖酵母中的ypt5基因，并恢复正常生长和生存能力。在哺乳动物细胞中表达的Ypt5蛋白与转铁蛋白受体共定位于早期内体。因此，早期内吞途径的分子层面在哺乳动物细胞和粟酒裂殖酵母之间可能是保守的，因此可能适合进行遗传分析。
