Kinetic and steady-state properties of fluorescence signals from the WT-DIII-VCF, E1784K-DIII-VCF, WT-DIV-VCF, and E1784K-DIV-VCF constructs.

<p>(<b>A1-A4</b>) Representative fluorescence signals for DIII-VCF, E1784K-DIII-VCF, DIV-VCF, and E1784K DIV-VCF constructs. Percentage of fluorescence change were calculated as ΔF/F0. (<b>B</b>) Voltage-dependence of steady state fluorescence signal change (FV) of WT-DIII-VCF and E1784K-DIII-VCF constructs. The E1784K mutant causes a shift in the DIII FV curve to more hyperpolarized membrane potentials. (<b>B <i>inset</i></b>) To measure the voltage-dependence of voltage-sensor fluorescence, the membrane potential of cells was changed to between -180mV and +20mV (a) from a holding potential of -120mV. (<b>C</b>) Voltage-dependence of steady state fluorescence signal change (FV) of WT-DIV-VCF and E1784K-DIV-VCF constructs. The E1784K mutant shifts the DIV FV curve in the hyperpolarizing direction.