The proton pumps of the plasmalemma and the tonoplast of higher plants.

Studies on intact cells, membrane vesicles, and reconstituted proteoliposomes have demonstrated in higher plants the existence of an ATP-driven electrogenic proton pump operating at the plasmalemma. There is also evidence of a second ATP-driven H+ pump localized at the tonoplast. The characteristics of both these ATP-driven pumps closely correspond to those of the plasmalemma and tonoplast proton pumps of Neurospora and yeasts.