Dependence of membrane current (relative to current in zero adenosine nucleotide) on [adenosine nucleotides] for wild-type and mutant channels (as indicated). Data points represent the mean ±s.e.m. (n = 3-10 patches). The data were fitted as described in Fig. 3. Ki for AMP = 1.8 mM (wild-type), 31.9 mM (Kir6.2ΔN2−30 + SUR1), and 13.6 mM (Kir6.2K185Q + SUR1). Not determined for Kir6.2ΔN2−30/K185Q + SUR1. Ki for ADP = 144 μM (wild-type), 1.1 mM (Kir6.2ΔN2−30 + SUR1), 2.5 mM (Kir6.2K185Q + SUR1), and 7.1 mM (Kir6.2ΔN2−30/K185Q + SUR1). Ki for adenosine tetraphosphate = 6 μM (wild-type), 124 μM (Kir6.2ΔN2−30 + SUR1), 680 μM (Kir6.2K185Q + SUR1), and 8.8 mM (Kir6.2ΔN2−30/K185Q + SUR1).