Na(+)/H(+) antiporter that extrudes sodium in exchange for external protons. Shows also high Ca(2+)/H(+) antiporter activity at alkaline pH. Does not catalyze exchange between Li(+) and H(+). Active over a wide pH range between 5 and 9. The C-terminal tail could affect ion specificity. Belongs to the monovalent cation:proton antiporter 1 (CPA1) transporter (TC 2.A.36) family.