Figure 4.

Characterization of α1α1_F64Cβ1γ2 receptor gating properties. A, Summary of the dependence of current amplitude (left) and decay kinetics (right) upon the ratio between α1 and α1_F64C overexpression. B, The 10–90% rise time of normalized α1α1_F64Cβ1γ2 (thick line) and α1β1γ2 (thin line) currents. C, Comparison of the deactivation kinetics between α1α1_F64Cβ1γ2 (left) and α1β1γ2 (right) normalized currents. D, Desensitization induced by 100 ms, 10 mm GABA pulse in α1α1_F64Cβ1γ2 (left) and α1β1γ2 (right) receptors. E, Desensitization induced by 3000 ms, 10 mm GABA pulse in α1α1_F64Cβ1γ2 (left) and α1β1γ2 (right). F, Currents elicited by two consecutive 10 ms pulses spaced by 100 ms from α1α1_F64Cβ1γ2 (left) and α1β1γ2 (right) receptors. G, Typical response of α1α1_F64Cβ1γ2 (left) and α1β1γ2 (right) currents to long (3000) ms conditioning pulse followed by a short (10 ms) test pulse. H, Summary of recovery from desensitization of paired pulse experiments shown in F. α1α1_F64Cβ1γ2 currents (black circles), at the considered time points, showed immediate recovery, while the α1β1γ2 receptors (open circles) displayed biexponential recovery (τ_fast = 8 ± 0.2 and τ_slow = 321 ± 21 ms, A_fast = 0.36 ± 0.03). I, Summary of recovery from desensitization of paired pulse experiments shown in G. Both α1α1_F64Cβ1γ2 currents (black squares) α1β1γ2 currents (open squares) showed biexponential recovery (τ_w = 27.3 ± 2.7 and τ_w 8.4 ± 1.1 s, respectively). J, Summary of the dependence of α1β1γ2- and α1α1_F64Cβ1γ2 currents deactivation kinetics on [GABA] (black, 1 ms pulse; gray, 20 ms pulse). K, Summary of the dependence of α1β1γ2- and α1α1_F64Cβ1γ2 currents onset kinetics on [GABA] (3000 and 20 ms pulses for black and gray, respectively). Each data point results from at least 20 recordings.