Faculty of Medicine, Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, Freiburg, D-79104, Germany.
BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, D-79104, Germany.
Bioessays. 2018 Jul;40(7):e1800013. doi: 10.1002/bies.201800013. Epub 2018 Apr 30.
Mitochondrial function and biogenesis depend on the transport of a large variety of proteins, ions, and metabolites across the two surrounding membranes. While several specific transporters are present in the inner membrane, transport processes across the outer membrane are less understood. Recent studies reveal that the number of outer membrane channels and their transport mechanisms are more diverse than originally thought. Four protein-conducting channels promote transport of distinct sets of precursor proteins across and into the outer membrane. The voltage-dependent anion channel (VDAC) forms the major channel for small hydrophilic molecules. In addition, three channels with yet unknown substrate specificity exist in the outer membrane. In this review, we outline the emerging functional diversity, selectivity, and regulation of mitochondrial outer membrane channels. The presence of several channel-forming proteins challenges the traditional view that the outer membrane forms an unspecific size-exclusion filter for the flux of small hydrophilic molecules.
线粒体的功能和生物发生依赖于大量蛋白质、离子和代谢物在这两层膜之间的跨膜运输。虽然在内膜中有几种特定的转运蛋白，但人们对外膜的转运过程了解较少。最近的研究表明，外膜通道的数量及其转运机制比最初认为的更加多样化。四种蛋白导运通道促进了不同组的前体蛋白穿过并进入外膜。电压依赖性阴离子通道（VDAC）形成了小分子亲水性物质的主要通道。此外，在外膜中还存在三种具有未知底物特异性的通道。在这篇综述中，我们概述了线粒体外膜通道的新兴功能多样性、选择性和调节。几种通道形成蛋白的存在挑战了传统观点，即外膜对小分子亲水性物质的流动形成了非特异性的大小排除过滤器。
