Panel A shows activation curves as data points with fitted curves of normalized conductance versus command potential with y-axis normalized GNa and x-axis command potential in millivolts for different constructs. Panel B is a scatter plot showing Vh values from fits of conductance voltage curves with y-axis Vh in millivolts and x-axis conditions. Panel C is a scatter plot showing z values from fits of conductance voltage curves with y-axis z value and x-axis conditions. Panel D shows inactivation curves as data points with fitted curves of time constants versus command potential with y-axis time constant in milliseconds and x-axis command potential in millivolts. Panel E shows time course current traces with y-axis normalized current and x-axis time in milliseconds. Panel F is a scatter plot comparing inactivation time constants at zero millivolts with y-axis time constant in milliseconds and x-axis conditions. Panel G shows steady state inactivation curves as data points with fitted curves of fractional availability versus command potential with y-axis fractional availability and x-axis command potential in millivolts. Panel H is a scatter plot showing Vh values for steady state inactivation with y-axis Vh in millivolts and x-axis conditions. Panel I is a scatter plot showing z values for steady state inactivation with y-axis z value and x-axis conditions.
Mutations in FGF14A N terminus that remove LTI still produce shifts in SSI and slow intrinsic fast inactivation. (A) GV curves for the indicated FGF14A constructs. (B and C) Vh and z values from fits of GV curves to individual cells. (D) Inactivation time constants at different voltages for mutant FGF14A constructs and FGF14B. (E) Example inactivation time courses for the indicated constructs plotted on a log scale, highlighting that most constructs produce slower inactivation onset compared with WT FGF14A, except for FGF14A_ΔNT. (F) Comparison of inactivation time constants at 0 mV, highlighting that N-terminal manipulations do not alter FGF14-mediated slowing of inactivation onset, except for complete deletion of NT (ΔNT). (G) Fractional availability curves for constructs with different N-terminal manipulations. (H and I) Vh and z values for SSI for different N-terminal manipulations. Statistical comparisons with P values are summarized in Table 5. *P < 0.05, **P < 0.01, and ****P < 0.0001.