Figure 4.
Mutations at specific sites in the γ subunit finger domain weaken inhibition by γ-11. Oocytes were injected with 1–4 ng/subunit of cRNA encoding the ENaC subunits indicated. Whole cell recordings of currents were performed 1 day later by TEVC at −60 mV. A, representative recordings of the effects of 0.5 and 1.5 μm γ-11 are shown. Na+ self-inhibition and peptide inhibition were determined as described in the legend to Fig. 2. Baseline currents (all on a αFβγΔI background) were −5.3 ± 2.5 μA for control, −1.3 ± 1.5 μA for G209W, −0.81 ± 0.51 μA for γT224W, and −1.2 ± 0.7 μA for N242W. B, Na+ self-inhibition values are plotted for individual experiments with the mean indicated by a bar. Data were log transformed prior to statistical analysis. C, values for inhibition by 1.5 μm γ-11 are plotted for individual experiments with the mean indicated by a bar. Data in B and C were analyzed by one-way ANOVA followed by Tukey's multiple comparison test. ***, p < 0.001; ****, p < 0.0001 versus control.