We have previously shown that vacuolar H+-ATPase subcomplex V(o) from mung bean contains subunit d, however, its sequence and function were unknown. In the present study, we report the cloning and recombinant over expression of subunit d from mung bean in E. coli. To study the function of subunit d, two vacuolar H+-ATPase subcomplexes V(o) from mung bean were purified-one containing subunits a and c(c',c") and the other containing subunits a, c(c',c") and d. After reconstitution of the purified V(o) subcomplexes into liposomes, the proton translocation was studied. Our results show that the V(o) subcomplex in the absence of subunit d is a passive proton channel, while the V(o) subcomplex in the presence of the subunit d is not. Taken together, our data supports the conclusion that the subunit d of the plant vacuolar H(+)-ATPase from mung bean is positioned at the central stalk and involved in the proton translocation across the tonoplast membrane.

中文翻译：

---

绿豆V-ATPase亚基d的克隆测序及其在被动质子转运中的作用[J].

我们之前已经表明，来自绿豆的液泡 H+-ATPase 亚复合体 V(o) 包含亚基 d，但是，其序列和功能未知。在本研究中，我们报告了绿豆亚基 d 在大肠杆菌中的克隆和重组过表达。为了研究亚基 d 的功能，纯化了来自绿豆的两个液泡 H+-ATPase 亚复合体 V(o)——一个含有亚基 a 和 c(c',c")，另一个含有亚基 a、c(c',c) ") 和 d。在将纯化的 V(o) subcomplexes 重组为脂质体后，研究了质子易位。我们的结果表明，没有亚基 d 的 V(o) 亚复合体是一个被动质子通道，而存在亚基 d 的 V(o) 亚复合体不是。综合起来，