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. Plays an important role in signal transduction (By similarity). Interacts with CHP1 and CHP2 (By similarity). Interacts with ARRB2. Expressed in brain, testis, spleen, and skeletal muscle. Phosphorylated (Possible). Belongs to the monovalent cation:proton antiporter 1 (CPA1) transporter (TC 2.A.36) family. The number, localization and denomination of hydrophobic domains in the Na(+)/H(+) exchangers vary among authors.