Figure 6.

Mutations of basic residues, but not acidic residues, alter the affinity of β4 peptides for Na channels. A, Mean currents evoked by resurgent current protocol in CA3 neurons with control mouse (gray) and mutant (black) β4 peptides, normalized to peak current evoked upon repolarization. Top, E13Q, n = 9; middle, E17Q, n = 7; bottom, K9R/K10R, n = 8. Insets, Mean currents normalized to peak transient current at +30 mV. Peptide schematics were rendered in Deepview (Swiss Institute of Bioinformatics). Gray indicates α carbon trace and control side chains (K2, F6, K9, K10, E13, K16, E17; others blanked for clarity). Black indicates side chains that deviate from control. B, Overlay of currents from A, normalized to resurgent current peak. C, Top, Mean amplitude of currents evoked at −30 mV after 10 ms conditioning step to +30 mV, normalized to transient current at +30 mV. Middle, Mean rise time of resurgent currents evoked at −30 mV. Bottom, Mean decay time constants (τ) of resurgent currents evoked at −30 mV.