Deshaies R J, Sanders S L, Feldheim D A, Schekman R
Division of Biochemistry and Molecular Biology, University of California Berkeley 94720.
Nature. 1991 Feb 28;349(6312):806-8. doi: 10.1038/349806a0.
Secretory-protein translocation into the endoplasmic reticulum (ER) is thought to be catalysed by integral membrane proteins. Genetic selections uncovered three Saccharomyces cerevisiae genes (SEC61, SEC62 and SEC63), mutations in which block import of precursor proteins into the ER lumen in vivo and in vitro. The DNA sequences of SEC62 and SEC63 predict multispanning membrane proteins, and biochemical characterization of the SEC62 protein (Sec62) confirms that it is an integral ER membrane protein. Here we show that Sec61, Sec62 and Sec63 are assembled with two additional proteins into a multisubunit membrane-associated complex. These results confirm previous predictions, based upon genetic interactions between the SEC genes, that Sec61, Sec62 and Sec63 act together to facilitate protein translocation into the ER.
分泌蛋白转运到内质网（ER）被认为是由整合膜蛋白催化的。遗传筛选发现了三个酿酒酵母基因（SEC61、SEC62和SEC63），这些基因的突变在体内和体外都会阻止前体蛋白导入ER腔。SEC62和SEC63的DNA序列预测它们是多跨膜蛋白，SEC62蛋白（Sec62）的生化特性证实它是一种内质网整合膜蛋白。在这里，我们表明Sec61、Sec62和Sec63与另外两种蛋白质组装成一个多亚基膜相关复合物。这些结果证实了基于SEC基因之间的遗传相互作用的先前预测，即Sec61、Sec62和Sec63共同作用以促进蛋白质转运到内质网中。
