Parameters determined from fitting Hill equation to GABA concentration-response relationships. Numbers in parentheses indicate number of oocytes tested. Concentration of GABA required for half-maximal activation (EC50) and Hill coefficient are mean ± S.D.
| Subunit | EC50μM | Hill Coefficient |
|---|---|---|
| ρ1(12) | 1.03 ± 0.26 | 2.26 ± 0.48 |
| β2 (10) | Reduced maximuma, b | |
| α1β2γ2(4) | 46.5 ± 4.7 | 1.52 ± 0.12 |
| Chimeras | ||
| ρ324/β283 (3) | 3.46 ± 4.7 | 1.52 ± 0.15 |
| ρ346/β305(3) | 4.58 ± 1.72 | 0.99 ± 0.17 |
| ρ405/β399 (4) | 0.54 ± 0.11 | 2.04 ± 0.32 |
| ρ268/β227–242/ρ285(3) | GABA activateda, b | |
| ρ324/β283–304/ρ347(6) | GABA activateda, b | |
| Point mutations | ||
| ρWV328,329MG (6) | 0.83 ± 0.17 | 2.22 ± 0.59 |
| ρWVS328–330MGC(7) | 1.06 ± 0.22 | 2.55 ± 0.52 |
| ρW328M(6) | 1.31 ± 0.30 | 2.39 ± 0.15 |
| ρV329G(4) | 0.42 ± 0.05 | 2.86 ± 0.65 |
| ρS330C(4) | 1.12 ± 0.15 | 2.35 ± 0.09 |
| ρVS329,330GC (3) | 0.23 ± 0.05 | 1.49 ± 0.06 |
| ρW328L (4) | 0.35 ± 0.22 | 2.62 ± 1.26 |
| ρW328I (4) | 0.39 ± 0.04 | 2.38 ± 0.19 |
| ρW328V (4) | 0.85 ± 0.01 | 3.13 ± 0.49 |
| ρW328A (6) | 31.74 ± 5.53 | 1.32 ± 0.08 |
| ρW328F (7) | 29.92 ± 4.44 | 1.51 ± 0.08 |
| ρW328Y (5) | 0.83 ± 0.06 | 3.05 ± 0.69 |
| ρW328E (12) | No response up to 30 mM | |
| ρW328S(10) | No response up to 30 mM | |
| ρW328P (11) | No response up to 30 mM | |
| ρY198S (4) | 3077.1 ± 724.2 | 1.56 ± 0.07 |
| ρY198S/W328M (3) | 3331.8 ± 346.7 | 1.61 ± 0.16 |
| ρY198S/WVS328–330MGC(6) | 2538.7 ± 616.0 | 1.52 ± 0.21 |
| βM286W(6) | Reduced maximuma, b | |
| βMGC286–288WVS (5) | Reduced maximuma, b | |
| ρWVS328–330GTC (3) | 7.69 ± 0.91 | 1.93 ± 0.10 |
| ρF333M(7) | No response up to 30 mM |
1-a Concentration-response relationship could not be fitted to these data points.
1-b Spontaneously open.