InterPro domain: IPR045016

This entry includes Na(+)/H(+) antiporter NhaD from bacteria and its homologue, NHD1/2 from Arabidopsis. In Vibrio cholerae, NhaD is a Na(+)/H(+) antiporter with a sharp maximum of activity at pH approximately 8.0 [ 1 ]. NhaD homologues have been found in plants. Physcomitrella patens PpNHAD1 has been shown to serve as a chloroplast transporter [ 2 ]. Expression of Mesembryanthemum crystalllinum NHAD has been shown to complement the Escherichia coli NhaA NhaB mutant, which lacks endogenous Na(+)/H(+) antiporters [ 3 ]. Arabidopsis NHD1 functions as a chloroplast sodium exporter and protects chloroplasts from deleterious Na+ concentrations after salt exposure [ 4 ].

1. Functional analysis of conserved polar residues in Vc-NhaD, Na+/H+ antiporter of Vibrio cholerae. J Biol Chem 280, 39637-43
2. Cloning of the PpNHAD1 transporter of Physcomitrella patens, a chloroplast transporter highly conserved in photosynthetic eukaryotic organisms. J Exp Bot 58, 2839-49
3. Na+/H+ antiporters are differentially regulated in response to NaCl stress in leaves and roots of Mesembryanthemum crystallinum. New Phytol 186, 669-80
4. Decreased capacity for sodium export out of Arabidopsis chloroplasts impairs salt tolerance, photosynthesis and plant performance. Plant J 78, 646-58