Abstract Mitochondria import the vast majority of their proteins via dedicated protein machineries. The translocase of the outer membrane (TOM complex) forms the main entry site for precursor proteins that are produced on cytosolic ribosomes. Subsequently, different protein sorting machineries transfer the incoming preproteins to the mitochondrial outer and inner membranes, the intermembrane space, and the matrix. In this review, we highlight the recently discovered role of porin, also termed voltage-dependent anion channel (VDAC), in mitochondrial protein biogenesis. Porin forms the major channel for metabolites and ions in the outer membrane of mitochondria. Two different functions of porin in protein translocation have been reported. First, it controls the formation of the TOM complex by modulating the integration of the central receptor Tom22 into the mature translocase. Second, porin promotes the transport of carrier proteins toward the carrier translocase (TIM22 complex), which inserts these preproteins into the inner membrane. Therefore, porin acts as a coupling factor to spatially coordinate outer and inner membrane transport steps. Thus, porin links metabolite transport to protein import, which are both essential for mitochondrial function and biogenesis.

中文翻译：

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孔蛋白作为线粒体蛋白质易位的助手

摘要 线粒体通过专用的蛋白质机器输入绝大多数蛋白质。外膜的转位酶（TOM 复合物）形成了在胞质核糖体上产生的前体蛋白的主要进入位点。随后，不同的蛋白质分选机器将传入的前蛋白转移到线粒体外膜和内膜、膜间隙和基质。在这篇综述中，我们强调了最近发现的孔蛋白（也称为电压依赖性阴离子通道（VDAC））在线粒体蛋白质生物发生中的作用。孔蛋白形成线粒体外膜中代谢物和离子的主要通道。已经报道了孔蛋白在蛋白质易位中的两种不同功能。第一的，它通过调节中央受体 Tom22 与成熟转位酶的整合来控制 TOM 复合物的形成。其次，孔蛋白促进载体蛋白向载体转位酶（TIM22 复合物）转运，后者将这些前蛋白插入内膜。因此，孔蛋白充当空间协调外膜和内膜转运步骤的耦合因子。因此，孔蛋白将代谢物转运与蛋白质输入联系起来，这对于线粒体功能和生物发生都是必不可少的。