Freitag H, Janes M, Neupert W
Eur J Biochem. 1982 Aug;126(1):197-202. doi: 10.1111/j.1432-1033.1982.tb06766.x.
Mitochondrial porin, the major protein of the outer mitochondrial membrane is synthesized by free cytoplasmic polysomes. The apparent molecular weight of the porin synthesized in homologous or heterologous cell-free systems is the same as that of the mature porin. Transfer in vitro of mitochondrial porin from the cytosolic fraction into the outer membrane of mitochondria could be demonstrated. Before membrane insertion, mitochondrial porin is highly sensitive to added proteinase; afterwards it is strongly protected. Binding of the precursor form to mitochondria occurs at 4 degrees C and appears to precede insertion into the membrane. Unlike transfer of many precursor proteins into or across the inner mitochondrial membrane, assembly of the porin is not dependent on an electrical potential across the inner membrane.
线粒体孔蛋白是线粒体外膜的主要蛋白质，由游离的细胞质多聚核糖体合成。在同源或异源无细胞系统中合成的孔蛋白的表观分子量与成熟孔蛋白相同。可以证明线粒体孔蛋白在体外从胞质部分转移到线粒体外膜中。在插入膜之前，线粒体孔蛋白对添加的蛋白酶高度敏感；之后则受到强烈保护。前体形式与线粒体的结合在4℃时发生，且似乎先于插入膜中。与许多前体蛋白转移到线粒体内膜或穿过线粒体内膜不同，孔蛋白的组装不依赖于内膜上的电势。
