Extremes of gating phenotypes of cysteine-substituted S2D4 mutants, F1385C and E1392C compared with wild-type channels.

A, Family of currents recorded from tsA201 cells expressing WT (left) and the most positively (F1385C, middle) and negatively perturbed mutant channels (E1392C, right) in terms of h_∞ (see 1C below). Current families were elicited by voltage pulses from a holding potential of −120 mV rendered in 5 mV increments. B, Current-voltage (G–V) relations for WT and mutant channels (E1392C, F1385C) in A. C, Availability-voltage (h_∞-V) relations for WT, F1385C (largest hyperpolarizing shift) and E1392C, (largest depolarizing shift). Symbols are normalized (I/I_max) values and solid lines are single Boltzmann fits to the data (most significant parameter perturbations contained in Table 1 the values for the entire set of mutant channels are contained in the Table A, Appendix S1)). D, Current decay time constants (τ_h). E, Recovery from inactivation time constants (τ_rec). The values for τ_h and τ_rec for the entire set of mutant channels are contained in the Table B Appendix S1.