Figure 2.

hENaC harboring the PHA-1-causing mutation, G70S, senses voltage. (A) Families of macroscopic Na⁺ currents from representative CHO cells expressing wild-type (top) and hENaC harboring the αG70S PHA-1 mutation (bottom). Currents were evoked by progressive 20 mV voltage steps from a holding potential of 0 mV up to 100 mV and down to −200 mV (voltage protocol shown in inset). For these experiments, the bath and pipette [Na⁺] were symmetrical at 150 mM. (B) Macroscopic I/V relations for CHO cells expressing wild-type (black line) and hENaC with the αG70S mutation (gray line). The I/V relations were generated from experiments similar to that in panel A. For presentation, the current was normalized to current at −100 mV. (C) Steady-state G-V relations fitted with the Boltzmann equation for CHO cells expressing wild-type (open squares) and hENaC containing αG70S (solid squares: developed from steady-state current at time 1 using voltage steps; open circles: developed from instantaneous tail currents at 80 mV at time 2). For presentation, conductance was normalized to the maximum of the fit. For B and C, n ≥ 9 for each group.