Table 1.
The α1(K278M) mutation affects the kinetics of GABA-induced desensitization and deactivation
| τfast (ms) | Amplitude τfast (% total) | τslow (ms) | |
|---|---|---|---|
| Desensitization | |||
| α1β2γ2 | 5.8 ± 1.4 | 58 ± 10% | 66 ± 8 |
| α1(K278M)β2γ2 | 5.7 ± 1.6 | 23 ± 6%* | 57 ± 12 |
| Deactivation | |||
| α1β2γ2 | 37 ± 17 | 45 ± 17% | 230 ± 83 |
| α1(K278M)β2γ2 | 4.7 ± 1.1* | 61 ± 9% | 20 ± 5* |
The sum of two exponentials was used to fit the desensitization and the deactivation phases of currents activated by 1 mm GABA (150 ms). Receptors containing the α1(K278M) mutation exhibited slower amplitude weighted time constants (τw) of desensitization (Fig. 8) due to a reduction in the amplitude of the fast component of desensitization (τfast). Receptors containing the α1(K278M) mutation exhibited a faster mean τw for deactivation (Fig. 8), an effect that was due to a reduction in the rate of both τfast and slow component (τslow) of deactivation. All data are represented as means ± SEM.
*
P < 0.05 compared to α1β2γ2 by Student's t test.