Fig. 6.

Evaluation of predicted and observed donor–acceptor distances (R). (A) RyR1 cryo-EM structural models (6, 7) showing proximities of apo-CaM (light blue) and Ca²⁺CaM (dark blue) to FKBP (green). Channel is shown in side view (Left) and top view (Right). (B) Predicted FRET between FKBP and the apo-CaM and Ca²⁺CaM species, based on proximities of FKBP and CaM centers of mass in cryo-EM models and the R₀ of the donor–acceptor pair. (C) Observed donor–acceptor distances derived from steady-state FRET measurements.