Benz R
Lehrstuhl für Biotechnologie, Universität Würzburg, Federal Republic of Germany.
Experientia. 1990 Feb 15;46(2):131-7. doi: 10.1007/BF02027308.
The matrix space of mitochondria is surrounded by two membranes. The mitochondrial inner membrane contains the respiration chain and a large number of highly specific carriers for the mostly anionic substrates of mitochondrial metabolism. In contrast to this the permeability properties of the mitochondrial outer membrane are by far less specific. It acts as a molecular sieve for hydrophilic molecules with a defined exclusion limit around 3000 Da. Responsible for the extremely high permeability of the mitochondrial outer membrane is the presence of a pore-forming protein termed mitochondrial porin. Mitochondrial porins have been isolated from a variety of eukaryotic cells. They are basic proteins with molecular masses between 30 and 35 kDa. Reconstitution experiments define their function as pore-forming components with a single-channel conductance of about 0.40 nS (nano Siemens) in 0.1 M KCl at low voltages. In the open state mitochondrial porin behaves as a general diffusion pore with an effective diameter of 1.7 nm. Eukaryotic porins are slightly anion-selective in the open state but become cation-selective after voltage-dependent closure.
线粒体的基质空间被两层膜包围。线粒体内膜包含呼吸链以及大量针对线粒体代谢中大多数阴离子底物的高度特异性载体。与此形成对比的是，线粒体外膜的通透性特性特异性要低得多。它作为一种分子筛，对亲水分子起作用，其明确的排阻极限约为3000道尔顿。线粒体外膜极高的通透性是由一种称为线粒体孔蛋白的成孔蛋白的存在所导致的。线粒体孔蛋白已从多种真核细胞中分离出来。它们是分子量在30至35 kDa之间的碱性蛋白质。重组实验确定它们的功能是成孔成分，在低电压下于0.1 M KCl中具有约0.40纳西门子（nS）的单通道电导。在开放状态下，线粒体孔蛋白表现为有效直径为1.7纳米的一般扩散孔。真核孔蛋白在开放状态下略有阴离子选择性，但在电压依赖性关闭后变为阳离子选择性。
