NhaC family

The NhaC family belongs to the Ion Transporter (IT) Superfamily. A representative list of proteins belonging to the NhaC family can be found in the .
Two members of the NhaC family have been functionally characterized. One is believed to be a Na⁺:H⁺ antiporter; the other is a malate·H⁺:lactate·Na⁺ antiporter. Several paralogues are found in Vibrio cholerae, and two paralogues are found encoded in the completely sequenced genomes of bothHaemophilus influenzae and Bacillus subtilis. ''E. coli lacks such a homologue. Pyrococcus species also have at least one homologue each. Thus, members of the NhaC family are found in both Gram-negative bacteria and Gram-positive bacteria as well as archaea. NhaC of B. firmus is 462 amino acyl residues long and possesses 12 putative transmembrane α-helical segments. MleN of B. subtilis'' also exhibits 12 putative TMSs.
The transport reaction catalyzed by NhaC is probably:

Na+ + nH+ ⇌ Na+ + nH+.

That catalyzed by MleN is probably:

Malate + H⁺ + Lactate + Na⁺ ⇌ Malate + H⁺ + Lactate + Na⁺