NhaB Na⁺:H⁺ antiporter of 513 aas and 11 or 12 TMSs.  NhaB is physiologically important when the level of NhaA activity is growth limiting, when nhaA is not sufficiently induced, and/or when NhaA is not activated (Pinner et al. 1993). The  stoichiometry of NhaB is 3H⁺/2Na⁺, different from that of NhaA (Pinner et al. 1994). It is required for intracellular pH regulation under alkaline conditions (Shimamoto et al. 1994). Mutations D146A/D404A in the Klebsiella pneumoniae ortholog changed the stoichiometry to a H⁺:Na⁺ ratio of < 1 (Patiño-Ruiz et al. 2019).