Small GTP-binding proteins associated with secretory vesicles of Paramecium.
Small GTP-binding proteins associated with secretory vesicles of Paramecium.
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与草履虫分泌囊泡相关的小 GTP 结合蛋白。
DOI：
10.1111/j.1550-7408.1991.tb04823.x
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
Peterson,JB
中科院分区：
文献类型：
--
作者：
Peterson,JB
GTP结合蛋白在包括分泌在内的各种膜相关过程中充当分子开关。一组GTP结合蛋白，20-30 kDa，与原癌基因产物相关。在酿酒酵母中，ras样GTP结合蛋白调节分泌中的囊泡运输。四脲草履虫（Parameciumtetraurelia）含有分泌囊泡，其蛋白质内容物通过调节胞吐作用释放.使用[α-32 P]GTP和GTP结合的印迹分析，我们在四脲草履虫提取物中检测到至少7种低分子量（22-31 kDa）的GTP结合蛋白。亚细胞组分包含这7种蛋白的特征子集;纤毛富集了最小的（22 kDa）。GTP结合蛋白的模式在两个突变体中发生了改变，这两个突变体在形成或排出囊泡方面存在缺陷。分离的毛孢囊（其周围膜完整）含有两种次要的GTP结合蛋白（23.5和29 kDa）和一种主要的GTP结合蛋白（23 kDa），这些蛋白在去膜毛孢囊中不存在。GTP结合蛋白的这种差异定位表明特异性GTP结合蛋白在纤毛运动和胞吐中的功能特化。
GTP‐binding proteins act as molecular switches in a variety of membrane‐associated processes, including secretion. One group of GTP‐binding proteins, 20–30 kDa, is related to the product of therasproto‐oncogene. InSaccharomyces cerevisiae, ras‐like GTP‐binding proteins regulate vesicular traffic in secretion. The ciliate protistParamecium tetraureliacontains secretory vesicles (trichocysts) whose protein contents are released by regulated exocytosis. Using [α‐32P]GTP and an on‐blot assay for GTP‐binding, we detected at least seven GTP‐binding proteins of low molecular mass (22–31 kDa) in extracts ofParamecium tetraurelia.Subcellular fractions contained characteristic subsets of these seven; cilia were enriched for the smallest (22 kDa). The pattern of GTP‐binding proteins was altered in two mutants defective in the formation or discharge of trichocysts. Trichocysts isolated with their surrounding membranes intact contained two minor GTP‐binding proteins (23.5 and 29 kDa) and one major GTP‐binding protein (23 kDa) that were absent from demembranated trichocysts. This differential localization of GTP‐binding proteins suggests functional specialization of specific GTP‐binding proteins in ciliary motility and exocytosis.