Fig. 2.

(a) Model of the transport domain of NHE1 showing the area of exchange as two opposing funnel structures facing the intracellular and extracellular surfaces with membrane spanning domains indicated by roman numerals with critical amino acids shown. (b) Comparison of NhaA and NHE1 transport domains, modeled from the crystal structure of NhaA. The homologus amino acids crucial to exchange of NhaA and NHE1 are show. (With permission from Donowitz et al., 2009, orginally from Landau et al., 2007)