Phosphatase activities of TI loop mutants.

(A) Representative currents traces of Ci-VSP WT and denoted mutants that were co-expressed with KCNQ2/KCNQ3 potassium channels in Xenopus oocytes. Channel currents were recorded in response to a depolarization pulse from a holding potential of −80 to+80 mV for the indicated time interval. (B–C) From the resulting current traces, maximal and minimal current amplitudes (I_max and I_min) were determined during the depolarization phase at+80 mV. Inhibition ratios calculated with the values of I_min and I_max are plotted with the corresponding time durations required for each mutant to inhibit the channel currents to 50% (τ_50%). Inhibition ratio of 0.5 (corresponding to 50%) is highlighted as dashed line.