FIGURE 3.

FRET in C-terminal constructs. A and B, capsaicin activates the C-terminally FP-labeled channels (A, n = 8), and the tandem dimer-FP constructs (B, n = 4) in a dose-dependent manner. Solid lines indicate the fit with the Hill equation. C, FRET between CFP and eYFP in the C terminus of TRPV1. The data are presented as the average of the efficiency in 0.1 intervals of the intensity ratio. Solid and dotted lines are the predictions for adjacent FPs separated by 6.6 ± 0.2 nm (r₁). D, FRET in a tetramer made of dimers with a single FRET pair at the C terminus; the prediction for a diagonal distance is 8 ± 0.6 nm (r₂).