Comparison of NhaA with NapA and ASBT_NM. (A) Structural comparison of NhaA and NapA. Cartoon representation of TMs 4, 5, 10, and 11 of NhaA superimposed on the same helices of NapA (Lee et al., 2013). Residue numbering is shown for NhaA. K300 in NhaA corresponds to K305 in NapA, and D163 in NhaA corresponds to D156 in NapA. The helices of the TMs in NhaA have been colored as in Fig. 3, and NapA is colored salmon. (B) Structural comparison of NhaA and ASBT_NM. Cartoon representation of TMs 4, 10, and 11 of NhaA superimposed on TMs 4, 8, and 9 of ASBT_NM (Hu et al., 2011). The helices of the TMs in NhaA have been colored as in A, and ASBT_NM is colored gray. The sodium Na2 site in ASBT_NM is depicted as a purple sphere, and Lys300 residue in NhaA is shown as a stick model.