PROTON AND POTASSIUM TRANSPORT BY H+/K+-ATPases

1. H⁺/K⁺-ATPases are members of the P-type ATPase multigene family. The prototypical H⁺/K⁺-ATPase is the protein that acidifies gastric luminal contents. The physiological and pharmacological significance of this pump has led to a detailed investigation of its biochemistry and molecular and cell biology. 2. Recently, a number of closely related H⁺/K⁺-ATPase isoforms have been discovered. These isoforms are present in organs other than the stomach, including the colon and kidney, where they contribute to acid—base and potassium homeostasis. The structure, expression and physiological roles of the gastric H⁺/K⁺-ATPase and other isoforms are reviewed.