FIGURE 6.

Mutations at sites in the late finger and top of the thumb of α ENaC affect Na⁺ self-inhibition. A, effect of Trp mutation at individual sites on Na⁺ self-inhibition, defined as 100·(1 − I_SS/I_Peak). Two Cys (C) residues in the thumb and three endogenous Trp (W) residues were not mutated. Values are mean ± S.D. (n = 5–12). Dashed line indicates wild-type value (37 ± 10%). p values versus wild-type channels were determined by analysis of variance with a Newman-Keuls post-hoc test. Values of p < 0.0001 were considered significant. B, helical wheel projection of residues 265–285. Mutations at residues that affected Na⁺ self-inhibition are gray. αTrp-278 was not mutated.