Sirrenberg C, Bauer M F, Guiard B, Neupert W, Brunner M
Institut für Physiologische Chemie der Universität München, Germany.
Nature. 1996 Dec 12;384(6609):582-5. doi: 10.1038/384582a0.
Translocation of mitochondrial preproteins across the inner membrane is facilitated by the TIM machinery. Tim23 binds to matrix targeting signals and initiates membrane potential-dependent import. Tim23 and Tim17 are constituents of a translocation channel across the inner membrane. Tim44 is associated with this channel at the matrix side, and Tim44 recruits mitochondrial Hsp70 and its co-chaperone Mgel, which drive protein translocation into the matrix using ATP as an energy source. Tim22 is a new component of the import machinery of mitochondria, which shares sequence similarity with both Tim23 and Tim17. Here we report that Tim22 is required for the import of proteins of the mitochondrial ADP/ATP carrier (AAC) family into the inner membrane. Members of the yeast AAC family are synthesized without matrix targeting signals. Tim22 is in an assembly of high relative molecular mass that is distinct from the Tim23-Tim17 complex. Import of proteins of the AAC family is independent of Tim23, and import of matrix targeting signals containing preproteins is independent of Tim22.
线粒体前体蛋白穿过内膜的转运由TIM机制促进。Tim23与基质靶向信号结合并启动膜电位依赖性导入。Tim23和Tim17是穿过内膜的转运通道的组成部分。Tim44在基质侧与该通道相关联，并且Tim44募集线粒体Hsp70及其共伴侣Mgel，它们以ATP作为能量来源驱动蛋白质转运到基质中。Tim22是线粒体导入机制的一个新组分，它与Tim23和Tim17都具有序列相似性。在此我们报道，Tim22是线粒体ADP/ATP载体（AAC）家族蛋白质导入内膜所必需的。酵母AAC家族成员在没有基质靶向信号的情况下合成。Tim22存在于一个与Tim23-Tim17复合体不同的高相对分子质量聚集体中。AAC家族蛋白质的导入不依赖于Tim23，而含有前体蛋白的基质靶向信号的导入不依赖于Tim22。
