Alconada A, Kübrich M, Moczko M, Hönlinger A, Pfanner N
Biochemisches Institut, Universität Freiburg, Germany.
Mol Cell Biol. 1995 Nov;15(11):6196-205. doi: 10.1128/MCB.15.11.6196.
The mitochondrial outer membrane contains import receptors for preproteins and a multisubunit general insertion pore. Several small outer membrane proteins (< 10 kDa) have been identified by their association with receptors or the general insertion pore, yet little is known about their function. Here, we present evidence that the biochemically identified Mom8b and the genetically identified Isp6 are identical. A deletion of Mom8b/Isp6 in Saccharomyces cerevisiae leads to (i) a delay of import of preproteins, (ii) stabilization of preprotein binding to receptors and the general insertion pore, and (iii) destabilization of the interaction between receptors and the general insertion pore. These results suggest that Mom8b supports the cooperativity between receptors and the general insertion pore and facilitates the release of preproteins from import components and thereby promotes efficient transfer of preproteins.
线粒体外膜含有前体蛋白的输入受体和一个多亚基的通用插入孔。一些小的外膜蛋白（<10 kDa）已通过与受体或通用插入孔的关联而被鉴定出来，但对其功能知之甚少。在此，我们提供证据表明，生化鉴定的Mom8b和基因鉴定的Isp6是同一蛋白。酿酒酵母中Mom8b/Isp6的缺失导致：（i）前体蛋白输入延迟；（ii）前体蛋白与受体及通用插入孔的结合稳定；（iii）受体与通用插入孔之间相互作用的不稳定。这些结果表明，Mom8b支持受体与通用插入孔之间的协同作用，促进前体蛋白从输入组件中释放，从而促进前体蛋白的有效转运。
