Potassium-transporting ATPase alpha chain 1 (ATP4A) (ATP4A)

The Potassium-transporting ATPase alpha chain 1 (ATP4A) is the catalytic subunit of the gastric proton pump, an integral membrane protein responsible for the final step of gastric acid secretion (UniProt P20648). Located in the apical membrane of parietal cells, it functions as a P-type ATPase that exchanges cytoplasmic H+ for extracellular K+ at the expense of ATP hydrolysis (StatPearls, Physiology, Gastric Secretion). This enzyme is the primary therapeutic target for managing acid-related disorders, including gastroesophageal reflux disease (GERD) and peptic ulcer disease (PubMed, PMID: 30074233). Pharmacological intervention typically involves proton pump inhibitors (PPIs) like omeprazole, which form covalent bonds with cysteine residues on the alpha subunit to irreversibly inhibit acid secretion (PubChem, CID 4594). Newer agents, known as potassium-competitive acid blockers (P-CABs), provide a reversible alternative by competing for the K+ binding site (NIH, PMC7336250). Long-term inhibition of this target is associated with clinical concerns such as hypergastrinemia, hypomagnesemia, and increased susceptibility to enteric infections (FDA, Safety Communications).

Other names

Gastric H+/K+ ATPase alpha subunitH+/K+ ATPase alpha subunitProton pump alpha subunitATP4APotassium-transporting ATPase alpha chain 1

The target is inhibited by two primary classes of drugs: Proton Pump Inhibitors (PPIs) and Potassium-Competitive Acid Blockers (P-CABs). PPIs are acid-activated prodrugs that form a covalent disulfide bond with cysteine residues on the alpha subunit, leading to irreversible inhibition of the H+/K+ exchange (StatPearls). In contrast, P-CABs bind reversibly and competitively to the potassium-binding site of the enzyme, providing a faster onset of acid suppression (PubMed, PMID: 29103926).