GABA concentration response relationships for wild-type and 6′ mutant GABAARs
GABA concentration response curves were generated by measuring currents induced by increasing agonist concentrations (0.1 μM–7 mM). Values are represented as the mean ± S.E.M. The EC50 is the agonist concentration that elicits half of maximal response. Currents were normalized to the maximal current, and response curves were produced by using nonlinear regression to the Hill equation. N is the number of oocytes tested for each receptor.
| Receptor | GABA EC50 | Hill Coefficient | Maximal Response | N |
|---|---|---|---|---|
| μM | nA | |||
| α2β2 | 41 ± 15 | 0.8 ± 00.1 | 4759 ± 324 | 5 |
| α2(T6′W)β2 | 11 ± 3 | 1.5 ± 00.7 | 4023 ± 500 | 6 |
| α2(T6′C)β2 | 7 ± 3 | 1.6 ± 1.0 | 3221 ± 288 | 3 |
| α2(T6′M)β2 | 88 + 8* | 0.9 ± 0.1 | 3836 ± 1385 | 3 |
| α2β2(T6′C) | 10 ± 3 | 2.0 ± 1.0 | 1884 ± 467* | 3 |
| α2β2γ2s | 56 ± 11 | 1.4 ± 0.1 | 5889 ± 945 | 3 |
| α2(T6′C)β2γ2s | 10 ± 7* | 0.9 ± 0.3 | 5748 ± 2144 | 3 |
| α2β2(T6′C)γ2s | 2 ± 1* | 1.6 ± 0.3 | 5226 ± 1685 | 3 |
| α2(T6′W)β2γ2s | 10 ± 1* | 2.0 ± 1.6 | 6043 ± 810 | 3 |
↵* p < 0.05, significant effect of mutation compared with respective wild-type receptor.