A novel Golgi membrane protein is part of a GTPase-binding protein complex involved in vesicle targeting
A novel Golgi membrane protein is part of a GTPase-binding protein complex involved in vesicle targeting
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DOI：
10.1093/emboj/19.17.4485
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发表时间：
2000-09-01
期刊：
影响因子：
11.4
通讯作者：
Gallwitz, D
中科院分区：
文献类型：
--
作者：
Matern, H;Yang, XP;Gallwitz, D
通过双杂交相互作用，蛋白质亲和力和定位研究，我们以前确定Yip 1 p，一个完整的酵母高尔基体膜蛋白能够结合Ras样GTPases Ypt 1 p和Ypt 31 p在其GDP结合构象。在进一步的双杂交筛选中，我们鉴定出Yif 1 p是Yip 1 p的相互作用因子，我们表明Yif 1 p是一种进化上保守的、必需的35.5 kDa跨膜蛋白，它与高尔基体膜上的Yip 1 p形成紧密复合物。Yif 1 p的亲水性N-末端的一半面向胞质溶胶，并且根据双杂交分析可以与转运GTP酶Ypt 1 p、Ypt 31 p和Sec 4p相互作用，但与Yip 1 p相反，这种相互作用对于Yin蛋白功能是不确定的。条件致死突变体中Yif 1 p功能的丧失导致内质网（ER）到高尔基体蛋白转运的阻断以及ER膜和40-50 nm囊泡的积累。遗传分析表明Yif 1 p作用于Yip 1 p的下游，推测Ypt GTdR与Yip 1 p-Yif 1 p复合物的结合是必需的。在囊泡对接和融合之前。
Through two-hybrid interactions, protein affinity and localization studies, we previously identified Yip1p, an integral yeast Golgi membrane protein able to bind the Ras-like GTPases Ypt1p and Ypt31p in their GDP-bound conformation. In a further two-hybrid screen, we identified Yif1p as an interacting factor of Yip1p, We show that Yif1p is an evolutionarily conserved, essential 35.5 kDa transmembrane protein that forms a tight complex with Yip1p on Golgi membranes. The hydrophilic N-terminal half of Yif1p faces the cytosol, and according to two-hybrid analyses can interact with the transport GTPases Ypt1p, Ypt31p and Sec4p, but in contrast to Yip1p, this interaction is dispensable for Yin protein function. Loss of Yif1p function in conditional-lethal mutants results in a block of endoplasmic reticulum (ER)-to-Golgi protein transport and in an accumulation of ER membranes and 40-50 nm vesicles. Genetic analyses suggest that Yif1p acts downstream of Yip1p, It is inferred that Ypt GTPase binding to the Yip1p-Yif1p complex is essential. for and precedes vesicle docking and fusion.