Figure 5.

Determination of the chemical component of the free energy and effect of the temperature on the conductance in 4ILT. (A) Global fitting of the voltage dependence of weighted 1/τ_act and 1/τ_deact for 4ILT. The data were fitted globally with the ratio of the forward and backward components of Eq. 1, α for activation and β for deactivation (see Materials and methods for full equations), assuming that α₀ = β₀. z_α was found to be null. The lines represent the curve from the best fit. The results of z_β, ΔG for 4ILT, and the heterotetramers are listed on Table II. ΔH was calculated from E_a and z (ΔH = (E_af − E_ab) + (z_α − z_β)FV) for V = 0, and TΔS was calculated from ΔG and ΔH (see Table II). (B) Right shift of the G-V with a decrease in temperature in 4ILT. Normalized G-V curve for a typical oocyte measured at temperatures of 19, 15, 10, and 5°C. The shift from 19 to 5°C was in averaged 7 ± 3 mV (n = 4). The conductance was calculated using the peak tail currents. The external and internal solutions contained 12 and 120 mM K⁺, respectively.