Alfonzo M, Racker E
Can J Biochem. 1979 Dec;57(12):1351-8. doi: 10.1139/o79-180.
We have studied the composition of ATP-driven proton pumps from bovine heart mitochondria and have reconstituted the oligomycin-sensitive ATPase complex from its individual components. The complex contains 9 to 10 subunits of which 5 are assembled in the soluble F1 protein, 2 are required for the attachment of F1 to the membrane and 2 form the proton channel within the membrane. With the help of information obtained from studies of the chloroplast and the bacterial proton pumps, we can tentatively assign a function to each of the subunits of the pump. The position of F1 outside of the membrane seen in electron micrographs of negatively stained preparations, does not appear to be an artifact. Evidence from immunological studies, chemical derivatizations as well as further electron microscopy (positive staining and freeze-etching), support this statement. We describe in this paper a 28 000-dalton polypeptide which has been isolated from the mitochondria membrane and is required for the reconstitution of oligomycin-sensitive ATPase and 32Pi-ATP exchange activity. We propose a mechanism of action of the proton pump in which the key energy-yielding reaction is the binding of Mg2+ to the protein. The function of the proton gradient is to displace Mg2+ from this site to permit cyclic repetition of the binding process. Essential for this scheme is the cyclic opening and closing of the proton channel. We have outlined our present approaches to test this hypothesis.
我们研究了牛心线粒体中ATP驱动质子泵的组成，并从其各个组分中重构了对寡霉素敏感的ATP酶复合体。该复合体包含9至10个亚基，其中5个组装在可溶性F1蛋白中，2个是F1附着于膜所必需的，另外2个形成膜内的质子通道。借助从叶绿体和细菌质子泵研究中获得的信息，我们可以初步为泵的每个亚基赋予功能。在负染色制剂的电子显微照片中看到的F1在膜外的位置，似乎不是假象。来自免疫学研究、化学衍生化以及进一步电子显微镜检查（正染色和冷冻蚀刻）的证据支持了这一说法。我们在本文中描述了一种28000道尔顿的多肽，它已从线粒体膜中分离出来，是重构对寡霉素敏感的ATP酶和32Pi-ATP交换活性所必需的。我们提出了一种质子泵的作用机制，其中关键的产能反应是Mg2+与蛋白质的结合。质子梯度的作用是将Mg2+从该位点置换出来，以允许结合过程的循环重复。该方案的关键是质子通道的循环开放和关闭。我们概述了目前检验这一假设的方法。
