Hydrogen potassium-transporting ATPase (H+/K+ ATPase)

The Hydrogen potassium-transporting ATPase, frequently referred to as the gastric proton pump, is a P-type ATPase enzyme that serves as the primary driver of gastric acid secretion. It functions as a heterodimer consisting of a catalytic alpha subunit (ATP4A) and a glycosylated beta subunit (ATP4B), which are expressed in the parietal cells of the stomach lining [1, 2]. The enzyme utilizes the energy from ATP hydrolysis to transport hydronium ions into the gastric lumen in exchange for potassium ions, maintaining the highly acidic environment necessary for protein digestion and pathogen defense [3, 4]. This pump is the definitive therapeutic target for managing acid-related conditions such as gastroesophageal reflux disease (GERD), peptic ulcer disease, and Zollinger-Ellison syndrome [5, 6]. Pharmacological intervention typically involves proton pump inhibitors (PPIs), which covalently and irreversibly bind to the enzyme, or potassium-competitive acid blockers (P-CABs), which provide reversible inhibition [5, 9]. While these treatments are highly effective, chronic suppression of the pump can lead to complications such as vitamin B12 deficiency, hypomagnesemia, and an increased risk of enteric infections [1, 5].

Other names

Gastric proton pumpH+/K+ ATPaseGastric H,K-ATPaseH+/K+ exchanging ATPaseProton pumpATP4A/ATP4B complex

Proton pump inhibitors (PPIs) are prodrugs that require acid activation to form a sulfenamide intermediate, which then covalently binds to cysteine residues (primarily Cys813) on the alpha subunit, leading to irreversible inhibition [1, 9]. Potassium-competitive acid blockers (P-CABs) inhibit the enzyme by binding reversibly to the potassium-binding site, providing a faster onset of action and more consistent acid suppression [5, 9].