Department of Medical Biochemistry, Semmelweis University, Budapest, Hungary.
J Neurosci Res. 2011 Dec;89(12):1897-904. doi: 10.1002/jnr.22659. Epub 2011 May 3.
It was recently shown that, in progressively depolarizing mitochondria, the F(0) -F(1) ATP synthase and the adenine nucleotide translocase (ANT) may change directionality independently from each other (Chinopoulos et al. [2010] FASEB J. 24:2405). When the membrane potentials at which these two molecular entities reverse directionality, termed reversal potential (Erev), are plotted as a function of matrix ATP/ADP ratio, an area of the plot is bracketed by the Erev_ATPase and the Erev_ANT, which we call "B space". Both reversal potentials are dynamic, in that they depend on the fluctuating values of the participating reactants; however, Erev_ATPase is almost always more negative than Erev_ANT. Here we review the conditions that define the boundaries of the "B space". Emphasis is placed on the role of matrix substrate-level phosphorylation, because during metabolic compromise this mechanism could maintain mitochondrial membrane potential and prevent the influx of cytosolic ATP destined for hydrolysis by the reversed F(0) -F(1) ATP synthase.
最近的研究表明，在线粒体逐渐去极化的情况下，F(0)-F(1)ATP 合酶和腺嘌呤核苷酸转位酶（ANT）可以独立于彼此改变方向（Chinopoulos 等人，[2010]FASEB J. 24:2405）。当这两个分子实体的反转方向的膜电位，称为反转电位（Erev），作为基质 ATP/ADP 比的函数绘制时，图中的一个区域由 Erev_ATPase 和 Erev_ANT 包围，我们称之为“B 空间”。两个反转电位都是动态的，因为它们取决于参与反应的反应物的波动值；然而，Erev_ATPase 几乎总是比 Erev_ANT 更负。本文综述了定义“B 空间”边界的条件。重点介绍基质底物水平磷酸化的作用，因为在代谢受损期间，这种机制可以维持线粒体膜电位并防止细胞质 ATP 流入，这些 ATP 用于逆转的 F(0)-F(1)ATP 合酶水解。
