Table 1.
Concentration–response properties of wild-type and mutant receptors
| α1β2γ2L wild-type Unlabelled Current | ΔF | A5m Current | ΔF | α1L127Cβ2γ2L Unlabelled Current | ΔF | A5m Current | ΔF | |
|---|---|---|---|---|---|---|---|---|
| Maximal response | 1.03 ± 0.03 | nd | 1.06 ± 0.07 | nr# | 0.98 ± 0.02 | nr# | 1.24 ± 0.09 | 1.16 ± 0.09 |
| EC50 | 4.6 ± 0.4 µM | nd | 4.6 ± 0.9 µM | 20 ± 1 µM | 117 ± 41 µM | 173 ± 60 µM | ||
| nH | 1.4 ± 0.1 | nd | 1.3 ± 0.3 | 1.2 ± 0.1 | 0.5 ± 0.1 | 0.8 ± 0.2 |
The concentration–response curves were fitted to: response = maximal response/(1 + EC50/[GABA])nH, where EC50 is the concentration of GABA producing a half-maximal reponse, and nH is the Hill slope of the curve. The data were normalized to the response at 100 µM GABA (wild-type receptors) or 3 mM GABA (mutant receptors). Data are from 3–9 oocytes. ΔF, fluorescence change; A5m, Alexa Fluor 546 C5 maleimide; nd, not determined; nr#, no ΔF response was observed in the presence of GABA. For more details please see text.