Fig. 5.

Comparison of FRET in samples containing intact SR membranes and solubilized, purified RyR1. (A) Coomassie-stained gel comparing 2 SR membrane and 2 RyR1 preparations. Arrow points to 565-kDa RyR1 monomer. (B and C) FRET between F-FKBP donor and acceptor attached within CaM's N lobe, C lobe, or central linker. Experiments shown in B and C examined the same preparations shown in A. Samples contained 800 nM F-CaM acceptor and either 30 nM or 30 μM Ca²⁺, as indicated. Asterisks indicate significant differences from corresponding values at 30 nM Ca²⁺. Data are means ± SE from 4 experiments.