Mechanisms of mitochondrial protein import.
Mechanisms of mitochondrial protein import.
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DOI：
10.1042/bse0360061
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发表时间：
2000-12
影响因子：
6.4
通讯作者：
D. Gordon;A. Dancis;D. Pain
中科院分区：
文献类型：
--
作者：
D. Gordon;A. Dancis;D. Pain
线粒体的大部分蛋白质都是从胞浆中输入的。大多数基质蛋白的前体形式以及一些IM和IMS蛋白都是在N端可切割信号序列的细胞质核糖体上合成的。包括IM载体蛋白在内的许多其他线粒体蛋白都含有内部靶向序列。三个多亚基易位酶，一个在OM中，两个在IM中，参与了导入过程。这些转位酶与胞浆伴侣蛋白、IMS中的伴侣样可溶性蛋白以及基质中的伴侣蛋白协同作用。将载体蛋白插入IM只需要膜电位。另一方面，前蛋白通过IM进入基质需要(I)膜电位，(Ii)发生在IM外侧的GTP水解，以及(Iii)发生在基质侧的依赖于ATP的相互作用。在输入后，大多数前蛋白的可切割信号序列被MPP一步移除。在某些情况下，信号序列的去除分两步完成：第一步是通过MPP，第二步是通过线粒体中间多肽酶或IM多肽酶。进口的蛋白质必须正确折叠才能发挥它们的功能。
Mitochondria import most of their proteins from the cytosol. Precursor forms of most matrix proteins as well as some IM and IMS proteins are synthesized on cytoplasmic ribosomes with N-terminal cleavable signal sequences. Many other mitochondrial proteins including IM carrier proteins contain internal targeting sequences. Three multisubunit translocases, one in the OM and two in the IM, participate in the import process. These translocases co-operate with cytosolic chaperones, chaperone-like soluble proteins in the IMS as well as chaperones in the matrix. Insertion of carrier proteins into the IM only requires a membrane potential. On the other hand, translocation of preproteins across the IM into the matrix requires (i) a membrane potential, (ii) GTP hydrolysis, which occurs at the outer side of the IM, and (iii) ATP-dependent interactions occurring at the matrix side. Following import, the cleavable signal sequence of most preproteins is removed in one step by the MPP. In some cases, removal of the signal sequence is achieved in two steps; first by MPP and second by either mitochondrial intermediate peptidase or by IM peptidases. Imported proteins must be folded properly to perform their functions.