Figure 3.

Po-voltage relationships. Po for full (A) and subconductance (B) openings as a function of voltage is shown for individual experiments. Model M2 was used to idealize the data. In (C), the mean data is shown for subconductance Po (squares) and full open state Po (triangles). The line corresponds to a Boltzmann fit to the Po in the full open state according to the equation:

$$Po\left(V\right)={\text{Po}}_{\text{max}}{\left\{1+\text{exp}\left(\left[\Delta G+zFV\right]/RT\right)\right\}}^{-1},$$

where ΔG is the internal free energy of opening, z is the effective gating charge, Po_max is the maximum Po, and F, R, and T have their usual meanings (fit parameters: Po_max = 0.08 ± 0.01, ΔG = 9.9 ± 1.3 kJ mol⁻¹, z = −7.3 ± 0.9). The negative z value indicates that negative charge moves in the trans (luminal) to cis (cytosolic) direction or that positive gating charge moves in the opposite direction as voltage increments from 0 to +20 mV. Mean values ± SE are shown. The following number of recordings were used at each voltage: −40 mV (3), −30 mV (8), −20 mV (2), 10 mV (7), 20 mV (12), 30 mV (17), 40 mV (10), and 50 mV (8). To see this figure in color, go online.