Fig. 7.

Neutralization mutants decrease the VSD-PD allosteric coupling. (A) Normalized tail current amplitude ($I_{\mathit{tail}}/I_{\mathit{tail},\mathit{max}}$) versus voltage relation for BK wt and the VSD neutralization variants. Colored solid lines represent the best fit to the H-A allosteric model, where $J_0$ and $z_J$ were obtained from experiments shown in Fig. 1 and $L_0$ and $z_L$ remained constant for all channels except for D186N, R207Q, and R210Q, where $z_L$ could vary to fit the experimental data. All parameter fitting is reported in SI Appendix, Table S2. (B) Allosteric coupling constant ±S.E. ($D$) between the VSD and the PD obtained from the fittings of the $I_{\mathit{tail}}/I_{\mathit{tail},\mathit{max}}$ data using Eq. 5.