Mediates electroneutral exchange of protons for Na(+) and K(+) across endomembranes. May contribute to the regulation of Golgi apparatus volume and pH. Interacts with SCAMP1, SCAMP2 and SCAMP5; may participate in its shuttling from trans-Golgi network to recycling endosomes. N-glycosylated. Belongs to the monovalent cation:proton antiporter 1 (CPA1) transporter (TC 2.A.36) family.