Gastric H+/K+-exchanging ATPase (H+/K+-ATPase)

The Gastric H+/K+-exchanging ATPase, commonly known as the gastric proton pump, is a P-type ATPase responsible for the final step of gastric acid secretion in the stomach. Located in the apical membrane of parietal cells, this heterodimeric enzyme (comprising alpha and beta subunits) exchanges cytoplasmic hydronium ions for extracellular potassium ions in an electroneutral process powered by ATP hydrolysis [1, 4]. This activity generates a massive proton gradient, maintaining the highly acidic environment (pH ~1.0) necessary for protein digestion and defense against ingested pathogens [6, 8]. Dysregulation or excessive activity of this pump contributes to acid-related disorders such as gastroesophageal reflux disease (GERD) and peptic ulcers [7, 10]. It is the primary therapeutic target for proton pump inhibitors (PPIs), which bind covalently and irreversibly to the enzyme, and newer potassium-competitive acid blockers (P-CABs), which inhibit the pump reversibly [2, 9]. Long-term pharmacological suppression of this target is associated with safety concerns including nutrient malabsorption and increased susceptibility to enteric infections [1, 7].

Other names

Gastric proton pumpProton pumpH+/K+ ATPaseGastric hydrogen potassium ATPaseATP4A/ATP4BAcid pump

Inhibition of gastric acid secretion through either irreversible covalent binding to cysteine residues (Proton Pump Inhibitors) or reversible competitive antagonism of the potassium-binding site (Potassium-Competitive Acid Blockers).