Figure 3. [ATP] dependence of N-terminal truncated K_ATP mutant channels.

Steady-state dependence of membrane current (mean ±s.e.m. relative to current in zero ATP) on [ATP] for wild-type and mutant channels (from records such as those shown in Fig. 2). Data points represent the mean ±s.e.m. (n = 3-8 patches). The fitted lines correspond to least-squares fit of the Hill equation (relative current = 100/(1 + ([ATP]/K_i)^n_H), with n_H fixed at 1.3, and K_i = 12 μM (wild-type), 44 μM (Kir6.2ΔN2-10), 36 μM (Kir6.2ΔN2-20 + SUR1), and 124 μM (Kir6.2ΔN2−30 + SUR1).