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/Imax) 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 (τh). E, Recovery from inactivation time constants (τrec). The values for τh and τrec for the entire set of mutant channels are contained in the Table B Appendix S1.