Involved in pH regulation to eliminate acids generated by active metabolism or to counter adverse environmental conditions. Major proton extruding system driven by the inward sodium ion chemical gradient. Seems to play an important role in colonic sodium absorption.
Expressed in skeletal muscle, colon and kidney. Lower levels in the testis, prostate, ovary, and small intestine.
Belongs to the monovalent cation:proton antiporter 1 (CPA1) transporter (TC 2.A.36) family.