Figure 3.

The allosteric effect correlates with binding to the head site. (A) Allosteric effects of the blockers on C-type inactivation. The inactivation rate in zero [K⁺] was measured as described in Fig. 1. The ratio of the rate without blocker to the rate with blocker is plotted. (B) The half-blocking concentration for each blocker was measured for ShakerΔ wild-type (WT) and for the two mutants T441S and T469I. The fold change in affinity, relative to wild type, is plotted for each of the two mutations. The left axis shows the corresponding change (ΔΔG) in ΔG_binding/kT. (ΔΔG = kT · ln (K_1/2{mutant}/K_1/2{wild type}).