Goud B, Salminen A, Walworth N C, Novick P J
Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06510.
Cell. 1988 Jun 3;53(5):753-68. doi: 10.1016/0092-8674(88)90093-1.
SEC4, one of the 10 genes involved in the final stage of the yeast secretory pathway, encodes a ras-like, GTP-binding protein. In wild-type cells, Sec4 protein is located on the cytoplasmic face of both the plasma membrane and the secretory vesicles in transit to the cell surface. In all post-Golgi blocked sec mutants, Sec4p is predominantly associated with the secretory vesicles that accumulate as a result of the secretory block. Sec4p is synthesized as a soluble protein that rapidly (t1/2 less than or equal to 1 min) and tightly associates with secretory vesicles and the plasma membrane by virtue of a conformational change of a covalent modification. These data suggest that Sec4p may function as a "G" protein on the vesicle surface to transduce an intracellular signal needed to regulate transport between the Golgi apparatus and the plasma membrane.
SEC4是参与酵母分泌途径最后阶段的10个基因之一，编码一种类Ras的GTP结合蛋白。在野生型细胞中，Sec4蛋白位于质膜的细胞质面以及转运至细胞表面的分泌小泡上。在所有高尔基体后阻断的sec突变体中，Sec4p主要与因分泌阻断而积累的分泌小泡相关联。Sec4p作为一种可溶性蛋白合成，它通过共价修饰的构象变化迅速（半衰期小于或等于1分钟）且紧密地与分泌小泡和质膜结合。这些数据表明，Sec4p可能在小泡表面作为一种“G”蛋白发挥作用，以转导调节高尔基体与质膜之间转运所需的细胞内信号。
