Hartl F U, Ostermann J, Guiard B, Neupert W
Institut für Physiologische Chemie, München, Federal Republic of Germany.
Cell. 1987 Dec 24;51(6):1027-37. doi: 10.1016/0092-8674(87)90589-7.
We investigated the import and sorting pathways of cytochrome b2 and cytochrome c1, which are functionally located in the intermembrane space of mitochondria. Both proteins are synthesized on cytoplasmic ribosomes as larger precursors and are processed in mitochondria in two steps upon import. The precursors are first translocated across both mitochondrial membranes via contact sites into the matrix. Processing by the matrix peptidase leads to intermediate-sized forms, which are subsequently redirected across the inner membrane. The second proteolytic processing occurs in the intermembrane space. We conclude that the hydrophobic stretches in the presequences of the intermediate-sized forms do not stop transfer across the inner membrane, but rather act as transport signals to direct export from the matrix into the intermembrane space.
我们研究了细胞色素b2和细胞色素c1的导入和分选途径，它们在功能上位于线粒体的膜间隙。这两种蛋白质在细胞质核糖体上作为较大的前体合成，并在导入线粒体时分两步进行加工。前体首先通过接触位点穿过线粒体的两层膜进入基质。基质肽酶的加工产生中等大小的形式，随后它们被重新引导穿过内膜。第二次蛋白水解加工发生在膜间隙。我们得出结论，中等大小形式的前序列中的疏水片段不会阻止其穿过内膜，而是作为转运信号指导其从基质输出到膜间隙。
