Figure 7.

Ca²⁺-dependent activation of Q559W_16F. (A) Exposure of Q559W_16F to 2 mM [Ca²⁺]_i for 3 min (indicated by the black line on top) revealed little current rundown. (B) Examining [Ca²⁺]_i-dependent activation of Q559W_16F (at +40 mV) in symmetrical 140 mM [Cl⁻] using the three-pulse protocol. A representative trace of the experiment using this protocol is shown on the right. The dashed line is the zero current level. Numbers and horizontal segments above the trace represent the application of the applied [Ca²⁺]_i in µM. (C) Dose–response curve of Ca²⁺-activation of Q559W_16F in symmetrical 140 mM Cl⁻. Various [Ca²⁺]_i were sequentially applied as shown by the recording trace shown on the right. In B and C, all currents were normalized to that obtained with 2 mM [Ca²⁺]_i (n = 10–15). The dashed curve was the fitted dose–response curve of WT_16F shown in Fig. 4.