FIGURE 8.

Dependence of WT and K210A on [NO₃⁻]_ext and voltage. A, dependence on [NO₃⁻]_ext of the normalized currents for WT (n ≥ 7, filled squares) and K210A (n ≥ 8, open circles) at 120 mV. Normalization was performed with the current in 100 mm Cl⁻ at 120 mV. Solid and dashed curves are fits to Equation 3, with K_1/2 and I_max^NO3−/I_max^Cl− as the fitted parameters resulting in values of 171 ± 26 and 372 ± 74 for K_1/2 and 2.9 ± 0.2 and 2.0 ± 0.2 mm for I_max^NO3−/I_max^Cl−, for WT and K210A, respectively. B, voltage dependence of K_1/2. Symbols are the same as in panel A. Lines are fit with Equation 4 with K(0) and z as the fitted parameters resulting in values of 3.2 ± 0.6 and 0.74 ± 0.07 m for WT and 11.9 ± 3.4 and 0.62 ± 0.05 m for K210A, respectively.