This family contains a number of bacterial Na+/H+ antiporter 1 proteins. These are integral membrane proteins that catalyse the exchange of H+ for Na+ in a manner that is highly dependent on the pH [1].

1: Expression of a sodium proton antiporter (NhaA) in Escherichia coli is induced by Na+ and Li+ ions. Karpel R, Alon T, Glaser G, Schuldiner S, Padan E; J Biol Chem 1991;266:21753-21759. PMID:1657980