Figure 8. The α1(K278M) mutant slows desensitization kinetics and increases deactivation rates.

A, exemplar traces showing rapid application of GABA (1 mm, 150 ms pulse duration) to outside-out patches containing α1β2γ2 (top trace) or α1(K278M)β2γ2 subunits (middle trace). After each experiment liquid junction currents were obtained by rupturing the patch and stepping the open tip across solutions containing dissimilar ions and are displayed above the corresponding GABA response. B, top graph, combined data demonstrating that the α1(K278M) mutant slows desensitization kinetics (n = 4). Bottom graph, combined data demonstrating that the α1(K278M) mutant accelerates deactivation kinetics (n = 4). Amplitude weighted values are provided here for simplicity. Desensitization and deactivation waveforms were fitted with double exponentials with fast and slow components (see Table 1 for all values). All data are represented as means ± SEM. *P < 0.05 compared to α1β2γ2 by Student's t test.