Endo Toshiya, Yamano Koji
Department of Chemistry, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
Biochim Biophys Acta. 2010 Jun;1803(6):706-14. doi: 10.1016/j.bbamcr.2009.11.007. Epub 2009 Nov 26.
Mitochondria are surrounded by two biological membranes. The outer mitochondrial membrane contains two major translocators, the TOM40 (TOM) and TOB/SAM complexes for protein translocation across and/or insertion into the outer membrane. The TOM40 complex functions as an entry gate for most mitochondrial proteins, and the TOB/SAM complex as a specialized insertion machinery for beta-barrel membrane proteins. In order to handle loosely folded or unfolded precursor polypeptides, those translocators cooperate with chaperones in the cytosol and intermembrane space, and also exhibit chaperone-like functions on their own. Several alpha-helical membrane proteins take 'non-standard' routes to be inserted into the outer membrane. Here we review the current view on a remarkable variety of mechanisms of protein transport taking place at the mitochondrial outer membrane.
线粒体被两层生物膜所包围。线粒体外膜包含两个主要的转运体，即用于蛋白质跨外膜转运和/或插入外膜的TOM40（TOM）复合体和TOB/SAM复合体。TOM40复合体作为大多数线粒体蛋白质的进入通道，而TOB/SAM复合体则作为β-桶状膜蛋白的特殊插入机制。为了处理松散折叠或未折叠的前体多肽，这些转运体与细胞质和膜间隙中的伴侣蛋白协同作用，并且自身也表现出类似伴侣蛋白的功能。几种α-螺旋膜蛋白通过“非标准”途径插入外膜。在这里，我们综述了目前关于线粒体外膜发生的多种蛋白质转运机制的观点。
