Activation enthalpy of CTX binding to open (left) and closed channels (right). The values of ΔH^≠ were estimates from Eq. 5. Cyan and pink bars denote measurements in Hi-Na⁺ and Hi-K⁺, respectively, while open and filled bars correspond to k_on and k_off, respectively. Error bars are the SE of the fit. See also Data S4 for a summary of experimental data in open channels and Datas S5 and S6 for underlying data.