NhaD family

The NhaD family belongs to the Ion Transporter (IT) Superfamily. A representative list of proteins belonging to the NhaD family can be found in the .
The NhaD Na⁺/H⁺ antiporter has been characterized from two Vibrio species: V. parahaemolyticus and V. cholerae and in the haloalkaliphile, Alkalimonas amylolytica. These proteins and their homologues are 400-500 aas long and exhibit 10-13 TMSs. They catalyze Na⁺/H⁺ and Li⁺/H⁺ antiport. They exhibit activity at basic pH with no activity at pH 7.5. The Amylolytica antiporter has low Na⁺ affinity and has optimal activity at 600 mM Na⁺. Homologues are found in Pseudomonadota of all groups, Flavobacteriia, and Chlamydia. Distant homologues of the IT superfamily are ubiquitous.
The generalized reaction catalyzed by NhaD is:

nH⁺ + mNa⁺ ⇌ nH⁺ + mNa⁺.