FIGURE 8.
G32R mutation reduced mean single channel open time of α1β3γ2L GABAA receptors by promoting occupancy of shorter lived open states. A, single channel currents were recorded from HEK293T cells expressing α1, γ2L, and either β3 (upper panel) or β3(G32R) (lower panel) subunits. Recording was conducted in the cell-attached configuration, with cells voltage-clamped at +80 mV and 1 mm GABA present in the recording electrode. B, single channel conductance (pA) was calculated for α1β3γ2L and α1β3(G32R)γ2L GABAA receptors. C, mean open time (ms) was calculated for α1β3γ2L and α1β3(G32R)γ2L GABAA receptors. D, frequency histograms of channel open durations were best fitted with three exponential functions. The left panel presents histograms for α1β3γ2L receptors, and the right panel presents histograms for α1β3(G32R)γ2L receptors. E, means of the three open durations (ms) were calculated. F, relative contribution (%) of each open state was calculated. All data are expressed as mean ± S.E., and significance was calculated using two-tailed Student's t test. *** indicates p < 0.001 compared with WT.