Nelson N
Roche Institute of Molecular Biology, Roche Research Center, Nutley, NJ 07110.
J Exp Biol. 1992 Nov;172:19-27. doi: 10.1242/jeb.172.1.19.
An electrochemical gradient of protons (PMF) is a universal high-energy intermediate in biological systems. Two related families of proton pumps, denoted F- and V-ATPases, are among the principal generators of a PMF from ATP and can form ATP at the expense of a PMF. The enzymes of these two families share a similar structure and subunit composition; some subunits in the two families evolved from common ancestors. Other subunits having no common ancestry were added independently to the various enzymes and defined the two separate families. The general mechanism for the proton pumping activity is similar in the two families. However, whereas F-ATPases can act in both proton pumping and ATP formation, the V-ATPases of eukaryotes function exclusively as ATP-dependent proton pumps. The catalytic and membrane sectors of F-ATPases and archaebacterial V-ATPases can separately catalyze their specific partial activities of ATPase and proton conduction. The catalytic and membrane sectors of the eukaryotic V-ATPases cannot act separately. This property is correlated with the presence of a large proteolipid that traverses the membrane four times. The gene duplication of the smaller proteolipid in the formation of the large proteolipid was one of the most important events in the evolution of the V-ATPases of eukaryotic cells.
质子电化学梯度（质子动力势）是生物系统中一种普遍存在的高能中间体。两类相关的质子泵家族，即F型和V型ATP酶，是由ATP产生质子动力势的主要来源，并且可以利用质子动力势合成ATP。这两个家族的酶具有相似的结构和亚基组成；两个家族中的一些亚基是由共同的祖先进化而来的。其他没有共同祖先的亚基则独立添加到各种酶中，从而定义了这两个不同的家族。这两个家族中质子泵活性的一般机制是相似的。然而，F型ATP酶既可以进行质子泵作用，也可以进行ATP合成，而真核生物的V型ATP酶仅作为依赖ATP的质子泵发挥作用。F型ATP酶和古细菌V型ATP酶的催化和膜结构域可以分别催化其ATP酶和质子传导的特定部分活性。真核生物V型ATP酶的催化和膜结构域不能单独发挥作用。这一特性与一种四次穿越膜的大的质子脂质体的存在有关。在大的质子脂质体形成过程中较小质子脂质体的基因复制是真核细胞V型ATP酶进化中最重要的事件之一。
