FIGURE 9.

Comparison of different models of the predicted transmembrane arrangement of the helix M9 and EL5 region of NHE1. Schematic representation of the transmembrane organization of NHE1 in the M9-EL5 region according to the models proposed by (A) Wakabayashi et al. (36) and (B) Landau et al. (65) that highlight functionally relevant amino acids identified in the present study. The red or green shading identifies sites that conferred sensitivity to MTS reagents or affected substrate affinities (Na⁺ and/or H⁺), respectively, when replaced with cysteine. Mutations of some sites affected both parameters and are dual labeled.