Plasma membrane H+-ATPase

The Plasma membrane H+-ATPase is a P-type ATPase enzyme located in the plasma membrane of plants, fungi, and some protists, but not in animal cells. It catalyzes the ATP-dependent extrusion of protons (H+) from the cytoplasm to the cell exterior, creating an electrochemical proton gradient (proton motive force). This gradient is essential for the uptake of nutrients and ions via secondary active transport, maintenance of membrane potential, pH homeostasis, and regulation of stomatal opening in plants. Structurally, it is a single polypeptide (~100 kDa) with 10 transmembrane segments and cytoplasmic N- and C-termini, often regulated through phosphorylation and interaction with 14-3-3 regulatory proteins. Multiple isoforms are encoded by gene families in plant genomes. The plasma membrane H+-ATPase is essential for plant viability, mediating critical roles in growth, nutrient uptake, and adaptation to environmental stress, although it is not implicated as a therapeutic target in humans.

Other names

H+-ATPasePM H+-ATPaseP-type H+-ATPasePlant plasma membrane H+-ATPaseProton pump (plants/fungi)Arabidopsis H+-ATPase (AHA, especially in *Arabidopsis thaliana*)

Inhibitors block the enzyme's ATPase activity, stopping proton extrusion and collapsing the proton gradient Activators (e.g., fusicoccin) lock the enzyme in an activated state by stabilizing the interaction with regulatory proteins and enhancing proton pumping