Comparisons of the effects of αR350W and other known gain–of–function human ENaC variants. ENaC activities and Na+ self-inhibition responses were examined in the same batches of oocytes expressing human ENaC αβγ (WT), αR350Wβγ, αC479Rβγ, or αW493Rβγ. A, normalized currents of WT, αC479R, αR350W, and αW493R mutants, obtained in three batches of oocytes with numbers of cells in parentheses. B, Iss/Ipeak of WT and the three variants, obtained in three batches of oocytes. Significantly different values in both A and B are noted (p < 0.0001, one-way ANOVA followed by Tukey's post hoc test). NS, not significant. C, locations of αArg-350, αTrp-493, and αCys-479 in a trimeric model of human ENaC. Three subunits (α, β, and γ) are shown as three colored ribbons, from PDB 6BQN (21), using PyMOL 2.0 (60). Three residues where the gain–of–function variants reside are shown as yellow spheres. D, zoomed-in view of the same model as C. For clarity, only αArg-350 in β7 of α-subunit and a partial palm domain of β-subunit are shown. Eight βENaC residues within 8 Å of the side chain of αArg-350, predicted by PyMOL, are shown. The dashed line identifies α/β-subunit interface.