Venema K, Palmgren M G
Department of Plant Biology, Royal Veterinary and Agricultural University, Frederiksberg, Copenhagen, Denmark.
J Biol Chem. 1995 Aug 18;270(33):19659-67. doi: 10.1074/jbc.270.33.19659.
The plasma membrane proton pump (H(+)-ATPase) of yeast energizes solute uptake by secondary transporters and regulates cytoplasmic pH. The addition of glucose to yeast cells stimulates proton efflux mediated by the H(+)- ATPase. A > 50-fold increase in proton extrusion from yeast cells is observed in vivo, whereas the ATPase activity of purified plasma membranes is increased maximally 8-fold after glucose treatment (Serrano, R. (1983) FEBS Lett. 156, 11-14). The low capacity of yeast cells for proton extrusion in the absence of glucose can be explained by the finding that, in H(+)-ATPase isolated from glucose-starved cells, ATP hydrolysis is essentially uncoupled from proton pumping. The number of protons transported per ATP hydrolyzed is significantly increased after glucose activation. We suggest that intrinsic uncoupling is an important mechanism for regulation of pump activity.
酵母的质膜质子泵（H(+)-ATP酶）通过次级转运蛋白为溶质摄取提供能量，并调节细胞质pH值。向酵母细胞中添加葡萄糖会刺激由H(+)-ATP酶介导的质子外流。在体内观察到酵母细胞的质子外排量增加了50倍以上，而葡萄糖处理后纯化质膜的ATP酶活性最大增加8倍（塞拉诺，R.（1983年）《欧洲生物化学学会联合会快报》156，11 - 14）。在没有葡萄糖的情况下酵母细胞质子外排能力较低，这可以通过以下发现来解释：从葡萄糖饥饿细胞中分离出的H(+)-ATP酶中，ATP水解基本上与质子泵浦解偶联。葡萄糖激活后，每水解一分子ATP转运的质子数显著增加。我们认为内在解偶联是调节泵活性的重要机制。
