Pfanner N, Hartl F U, Neupert W
Institut für Physiologische Chemie, Universität München, Federal Republic of Germany.
Eur J Biochem. 1988 Aug 1;175(2):205-12. doi: 10.1111/j.1432-1033.1988.tb14185.x.
Translocation of precursor proteins from the cytosol into mitochondria is a multi-step process. The generation of translocation intermediates, i.e. the reversible accumulation of precursors at distinct stages of their import pathway into mitochondria ('translocation arrest'), has allowed the experimental characterization of distinct functional steps of protein import. These steps include: ATP-dependent unfolding of precursors; specific recognition of precursors by distinct receptors on the mitochondrial surface; interaction of precursors; specific recognition of precursors by distinct receptors on the mitochondrial surface; interaction of precursors with a general insertion protein ('GIP') in the outer mitochondrial membrane; membrane-potential-dependent translocation into the inner membrane at contact sites between both membranes; proteolytic processing of precursors; and intramitochondrial sorting of precursors via the matrix space ('conservative sorting'). The functional characteristics unveiled by studying mitochondrial protein import appear to be of general interest for investigations on intracellular protein sorting.
前体蛋白从细胞质转运到线粒体是一个多步骤过程。转运中间体的产生，即前体蛋白在其导入线粒体途径的不同阶段的可逆积累（“转运停滞”），使得能够对蛋白质导入的不同功能步骤进行实验表征。这些步骤包括：前体蛋白的ATP依赖性解折叠；线粒体表面不同受体对前体蛋白的特异性识别；前体蛋白的相互作用；线粒体表面不同受体对前体蛋白的特异性识别；前体蛋白与线粒体外膜中的一般插入蛋白（“GIP”）的相互作用；膜电位依赖性转运到内外膜接触位点的内膜中；前体蛋白的蛋白水解加工；以及前体蛋白通过基质空间的线粒体内部分选（“保守分选”）。通过研究线粒体蛋白导入所揭示的功能特性似乎对细胞内蛋白分选的研究具有普遍意义。
