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. 2006 Jul 27;576(Pt 3):739–754. doi: 10.1113/jphysiol.2006.115105

Figure 6. Double cysteine substitution has little effect on the kinetics of fast inactivation.

Figure 6

The voltage-clamp protocols are provided as insets in Figure 2. A, voltage dependence of steady-state fast inactivation of the double mutants did not differ from the wild type. The data were fitted with a Boltzmann equation with midpoints (mmV) of −54.2 ± 1.2, −55.2 ± 1.0, −53.7 ± 1.4, −55.3 ± 1.8 and −52.7 ± 1.4, and slope factors (mV) of 6.7 ± 0.6, 5.5 ± 0.2, 5.5 ± 0.2, 5.2 ± 0.4, 5.2 ± 0.2 for E403C + E758C (n = 4), E403C + D1241C (n = 8), E403C + D1532C (n = 9), E758C + D1241C (n = 5), D1241C + D1532C (n = 4), respectively; compared with 53.0 ± 1.8 and 6.0 ± 0.3 for WT (n = 5). B, kinetics of recovery from fast inactivation in double-mutant channels were not changed compared with the wild type. The time constants were 2.5 ± 0.1 ms, 2.43 ± 0.2 ms, 2.3 ± 0.1 ms, 2.5 ± 0.4 ms and 2.2 ± 0.1 ms for E403C + E758C (n = 5), E403C + D1241C (n = 7), E403C + D1532C (n = 5), E758C + D1241C (n = 3), D1241C + D1532C (n = 4), respectively; compared with 2.4 ± 0.04 for WT.