Figure 1.

Gating properties of WT anthrax channels in lipid bilayers. (A) Family of traces elicited by a tail current protocol using 1-s test pulses to voltages ranging from −100 to +100 mV from a holding potential of −100 mV, followed by a 1-s tail pulse to −20 mV. (B) Tail currents at −20 mV were measured 20 msec into each tail epoch to account for the capacitance transient, normalized to their maximum value, and plotted against the test pulse voltage. The points in each dataset represent the mean ± SEM of three experiments. Solid line is the fit to a Boltzmann function (Eq. 1) with V₀ = −12 mV and z = 1.7. (C) Family of traces elicited by 2.5-s test pulses ranging from −100 to + 100 mV, from a holding potential of 0 mV. (D) Instantaneous current voltage measurements (circles) were taken 20 msec after each test pulse, and quasi steady-state measurements (diamonds) were taken at the end of the 2.5-s pulse. All experiments were in symmetric solutions of 20 mM MES, 100 mM KCl, 1 mM EDTA, pH 6.6.