Gastric H+,K+-ATPase alpha subunit (None (commonly abbreviated as HKA α or ATP4A in gene nomenclature, but no single universally adopted abbreviation))

Gastric H+,K+-ATPase alpha subunit is the catalytic enzyme responsible for gastric acid secretion in the stomach. It is part of a heterodimeric complex (with a beta subunit) embedded in the parietal cell membrane. The enzyme uses ATP hydrolysis to exchange intracellular protons (H+) for extracellular potassium ions (K+), an essential function for maintaining the highly acidic gastric environment necessary for digestion. The alpha subunit contains the ATP and cation binding domains, ten transmembrane segments, and a lysine residue crucial for proton translocation. The action of the proton pump can be potently inhibited by several classes of drugs, notably the proton pump inhibitors (PPIs), which are mainstays in the treatment of acid-related diseases, and by newer potassium-competitive acid blockers. Disruption of its activity is directly linked to various gastric pathologies and represents a validated therapeutic target for reducing gastric acid secretion[1][2][4][5].

Other names

Proton pump alpha subunitH+,K+-ATPase alpha chainGastric proton pump alpha subunitATPase, H+/K+ exchanging, alpha polypeptide (gene: ATP4A)

Irreversible inhibition of the enzyme's acid secretion activity by covalent binding (proton pump inhibitors: omeprazole, pantoprazole, etc.)[1][2] Reversible competitive inhibition at the potassium binding site (K+-competitive acid blockers, e.g., vonoprazan, SCH28080, BYK99)[4]