Comparison of the observed and predicted voltage dependence of Po for BK_B channel DM4 on linear and log-linear coordinates for the indicated gating mechanisms with saturating Ca²⁺_i. Open circles, observed voltage dependence; lines, predicted voltage dependence. A, linear coordinates; B, log-linear coordinates. Saturating Ca²⁺_i. The predictions of Schemes V and V_F (green and black lines) superimpose over most of the voltage range and give a somewhat more accurate description of the data at negative voltages than the other schemes.