Figure S1. The method of the estimation... | Rockefeller University Press

Figure S1.

$The method of the estimation of fractional fast inactivation in KCNQ1 channels. (A) Sample current traces in 20 mM external K+ conditions elicited by the voltage protocol shown below the traces. Calculation of the fractional inactivation for the red traces is demonstrated on the right side. The tail currents were fitted to three exponential functions of the form ao + a1e-t/τ1 + a2e-t/τ2 +a3e-t/τ3 between two cursors positioned immediately after capacitive transient (typically 5–10 ms after the segment start) and at 97% of the segment. (B) Enlarged view of the tail currents and corresponding exponential components of the fit. The sum of two exponential components with negative amplitudes (a1 and a2) together with constant amplitude a0 (black dashed curve) was extrapolated to the beginning of the segment. The intercept with the y axis was nominated as Y (represents total current amplitude). The initial current immediately after the capacitive transient was designated as X (represents the current of open channels at this time point). Fractional inactivation was calculated as 1 − X/Y.$

The method of the estimation of fractional fast inactivation in KCNQ1 channels. (A) Sample current traces in 20 mM external K⁺ conditions elicited by the voltage protocol shown below the traces. Calculation of the fractional inactivation for the red traces is demonstrated on the right side. The tail currents were fitted to three exponential functions of the form ao + a1e-t/τ1 + a2e-t/τ2 +a3e-t/τ3 between two cursors positioned immediately after capacitive transient (typically 5–10 ms after the segment start) and at 97% of the segment. (B) Enlarged view of the tail currents and corresponding exponential components of the fit. The sum of two exponential components with negative amplitudes (a1 and a2) together with constant amplitude a0 (black dashed curve) was extrapolated to the beginning of the segment. The intercept with the y axis was nominated as Y (represents total current amplitude). The initial current immediately after the capacitive transient was designated as X (represents the current of open channels at this time point). Fractional inactivation was calculated as 1 − X/Y.