Possible subunit of Na+/H+ antiporter [1], [2]. Predicted integral membrane protein, usually four transmembrane regions in this domain. Often found in bacterial NADH dehydrogenase subunit.

1: A putative multisubunit Na+/H+ antiporter from Staphylococcus aureus. Hiramatsu T, Kodama K, Kuroda T, Mizushima T, Tsuchiya T; J Bacteriol 1998;180:6642-6648. PMID:9852009

2: Mrp-dependent Na(+)/H(+) antiporters of Bacillus exhibit characteristics that are unanticipated for completely secondary active transporters. Ito M, Guffanti AA, Krulwich TA; FEBS Lett 2001;496:117-120. PMID:11356194