Summary of the effects of 1 μM 3α5αP on intracluster closed times from the α1β2γ2L wild-type receptor and α1Q241W, α1Q241L, and α1Q241S mutant receptors
The intracluster closed-time histograms were fitted to sums of three exponentials. In the wild-type receptor, 3α5αP potentiates the currents by decreasing the prevalence of the longest-lived closed-time component, CT3. In addition, the presence of steroid influences the mean duration of CT1 and the prevalence of CT2. The presence of steroid was without effect on the properties (mean durations and fractions) of intracluster closed times from the α1Q241W receptor. In receptors containing the α1Q241L mutation, 3α5αP affected the fraction of CT1. In receptors containing the α1Q241S mutation, 3α5αP affected the mean duration and fraction of CT1, and the fraction of CT2. Wild-type data are from Li et al. (2007b). The statistical analysis applies to the effect of the steroid for a given receptor (wild-type or mutant).
| Mutation | GABA | 3α5αP | CT1 | Fraction CT1 | CT2 | Fraction CT2 | CT3 | Fraction CT3 | n |
|---|---|---|---|---|---|---|---|---|---|
| μM | μM | ms | ms | ms | |||||
| None | 50 | 0.15 ± 0.01 | 0.60 ± 0.10 | 1.5 ± 0.2 | 0.13 ± 0.05 | 14.4 ± 4.2 | 0.27 ± 0.06 | 4 | |
| None | 50 | 1 | 0.22 ± 0.04* | 0.64 ± 0.12 | 1.4 ± 0.2 | 0.30 ± 0.10* | 14.3 ± 1.2 | 0.05 ± 0.01*** | 4 |
| α1Q241W | 10 | 0.13 ± 0.01 | 0.58 ± 0.07 | 1.9 ± 0.4 | 0.27 ± 0.04 | 20.3 ± 2.0 | 0.15 ± 0.04 | 4 | |
| α1Q241W | 10 | 1 | 0.16 ± 0.03 | 0.55 ± 0.15 | 1.8 ± 0.3 | 0.24 ± 0.04 | 19.7 ± 9.6 | 0.21 ± 0.11 | 3 |
| α1Q241L | 50 | 0.22 ± 0.05 | 0.54 ± 0.02 | 2.0 ± 1.1 | 0.17 ± 0.05 | 11.3 ± 2.7 | 0.29 ± 0.05 | 4 | |
| α1Q241L | 50 | 1 | 0.17 ± 0.03 | 0.61 ± 0.05* | 1.2 ± 0.3 | 0.13 ± 0.03 | 13.2 ± 5.6 | 0.25 ± 0.04 | 3 |
| α1Q241S | 50 | 0.21 ± 0.03 | 0.70 ± 0.07 | 1.5 ± 0.5 | 0.10 ± 0.02 | 14.4 ± 2.7 | 0.20 ± 0.05 | 7 | |
| α1Q241S | 50 | 1 | 0.14 ± 0.03** | 0.63 ± 0.04* | 1.4 ± 0.3 | 0.18 ± 0.05** | 14.6 ± 6.9 | 0.19 ± 0.03 | 6 |