线粒体中钾离子的转运

K+ transport in mitoplasts.

作者信息

Chang H S, Diwan J J

出版信息

Biochim Biophys Acta. 1982 Aug 20;681(2):220-5. doi: 10.1016/0005-2728(82)90025-1.

Abstract

K+ transport into mitoplasts, prepared by digitonin disruption and removal of the outer membranes from rat liver mitochondria, has been studied. Unidirectional K+ influx has been measured by means of 42K, in the presence of the respiratory substrate succinate. K+ influx is inhibited by CN-, antimycin A and dicyclohexylcarbodiimide, but is insensitive to oligomycin. A linear dependence of the reciprocal of the K+ -influx rate on the reciprocal of the external K+ concentration is observed. Under the conditions studied, the apparent Km for K+ of the transport mechanism is approx. 6 mM, while the Vmax of K+ influx is approx. 5 mu mol K+/g protein per min. The rate of K+ influx increases with increasing external pH over the range from 6.8 to 8.0. The observed kinetics, pH dependence and inhibitor sensitivity are essentially similar to previously reported characteristics of K+ transport into intact rat liver mitochondria. It is concluded that the outer mitochondrial membrane does not not have a role in controlling K+ flux into rat liver mitochondria.

摘要

研究了通过用洋地黄皂苷破坏大鼠肝线粒体并去除外膜制备的线粒体中钾离子（K⁺）的转运情况。在呼吸底物琥珀酸存在的情况下，利用⁴²K测量了单向K⁺内流。K⁺内流受到氰化物（CN⁻）、抗霉素A和二环己基碳二亚胺的抑制，但对寡霉素不敏感。观察到K⁺内流速率的倒数与外部K⁺浓度的倒数呈线性关系。在所研究的条件下，转运机制对K⁺的表观米氏常数（Km）约为6 mM，而K⁺内流的最大反应速度（Vmax）约为5 μmol K⁺/g蛋白质每分钟。在6.8至8.0的范围内，K⁺内流速率随着外部pH值的升高而增加。观察到的动力学、pH依赖性和抑制剂敏感性与先前报道的K⁺转运到完整大鼠肝线粒体中的特征基本相似。得出的结论是，线粒体外膜在控制K⁺流入大鼠肝线粒体方面不起作用。