Individual VSD movements are tracked by voltage clamp fluorometry. (A) Diagrams showing the previously identified locations used for TMR labeling in all four VSDs. (B–E) Fluorescent signals from DI (B), DII (C), DIII (D), and DIV (E). Signals were filtered at 1 kHz offline. Insets with black boundaries show the normalized fluorescent signal comparison of WT (gray) and CW (colored) at the most depolarized voltage tested (20 mV). Note in C, DII VSD deactivation showed a significant slow component that was not present in WT. Data plotted as Mean ± SEM. Amplitude measured as ∆F/F. The direction of the arrow indicts direction of fluorescent changes.