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. 1999 Feb 15;515(Pt 1):19–30. doi: 10.1111/j.1469-7793.1999.019ad.x

Figure 6. ATP dose-response relationship and mean peak open probability of N-terminal deletion and K185Q mutant channels.

Figure 6

A, steady-state dependence of membrane current (relative to current in zero ATP) on [ATP] for wild-type and mutant channels (as indicated) co-expressed with SUR1. Data points represent the mean ±s.e.m. (n = 3-8 patches). The data were fitted as described in Fig. 3. Ki = 12 μM (wild-type), 124 μM (Kir6.2ΔN2−30 + SUR1), 308 μM (Kir6.2K185Q + SUR1), 304 μM (Kir6.2ΔC25/K185Q + SUR1), and 4.9 mM (Kir6.2ΔN2−30/K185Q + SUR1). B, mean peak open probability (Po) of mutant Kir6.2 subunits was measured in the absence of inhibitory ATP by steady-state noise analysis using eqn (1) (see Methods). Asterisks denote statistical difference between wild-type Po,max and mutant channel Po,max using Student's unpaired t test (*P < 0.05). Peak open probabilities (Po) were as follows (n = 4-7 patches; ±s.e.m.): Kir6.2wt = 0.57 ± 0.08; K185Q = 0.56 ± 0.08; ΔN2-30 = 0.86 ± 0.02; ΔN2-30/K185Q = 0.83 ± 0.03; ΔC25 alone = 0.14 ± 0.02; ΔN2-30/ΔC25 alone = 0.17 ± 0.02.