Hydrogen-potassium ATPase alpha subunit (H+/K+ ATPase alpha subunit)

The hydrogen-potassium ATPase alpha subunit is the catalytic component of the gastric proton pump that exchanges cytoplasmic hydronium ions for extracellular potassium ions via ATP hydrolysis, serving as the final step in gastric acid secretion. It is encoded by the ATP4A gene and structurally consists of approximately 1,000 amino acids, incorporating multiple transmembrane domains. The enzyme functions as an α,β-heterodimer with the β subunit stabilizing and targeting the complex to the membrane. This ATPase is the principal target for proton pump inhibitors (PPIs), which revolutionized the treatment of peptic ulcer disease and acid reflux disorders by blocking acid secretion at its source.

Other names

Gastric H+/K+ ATPaseH,K-ATPase alpha subunitATP4AProton pump alpha subunit

Inhibition of gastric acid secretion by covalent or competitive binding to the pump, blocking the catalytic cycle and ion transport. Irreversible inhibition (PPIs covalently modify the enzyme). Reversible inhibition (potassium-competitive inhibitors).