BK currents in Xenopus oocytes following injection of a 1:1 mixture of G375R mutant and WT cRNA activate at greatly left-shifted negative voltages compared with BK currents following injection of only WT cRNA. I-V plots for the indicated injections of cRNA and blank. Two-electrode whole-cell voltage clamp. These currents were used to calculate the relative conductance plotted in Fig. 2. Protocol details are in Fig. 2 legend. The amount of WT cRNA injected was 25 times greater than for the injection of the 1:1 mixture of G375R mutant and WT cRNA so that the initial deviation of WT currents from the baseline could be readily detected. Mean ± SEM, n = 4 in each case.