Figure 3.

Inactive mutants can be rescued by coexpression. (A) Representative currents recorded from an inside-out membrane patch containing Kir6.2[L157C] + SUR1 channels (L157C, above) and from a patch containing mutant Kir6.2[L157C] and Kir6.2[R177A] subunits coexpressed with SUR1 (L157C + R177A, below). (B) Steady state dependence of membrane current on [ATP] (relative to current in zero ATP) for patches as in A and for coexpressed Kir6.2[L157C] and Kir6.2[K222A] subunits, with SUR1 (mean ± SEM, n = 5–7). The data were fit using a Hill equation (relative current=11+ATPK₁₂ ^H), with K_1/2,ATP = [ATP] causing half-maximal inhibition and H free to vary. Dashed line indicates relationship for wild-type Kir6.2 + SUR1 (WT).