FIGURE 4.

Comparison of the I_Y*/I_C FRET ratios in the absence (dyspedic) and presence (dysgenic) of RyR1. Error bars indicate S.D., and asterisks indicate constructs for which there was a significant (p < 0.001) difference in the I_Y*/I_C ratio between dyspedic (dysp.) and dysgenic (dysg.) myotubes. Note that the presence of RyR1 increased FRET between the N terminus and both the I-II loop (a) and II-III loop (b), as well as between the I-II and II-III loops (d); the presence of RyR1 decreased FRET between the II-III loop and C terminus (f) and had no significant effect on FRET between the N and C termini (c). There was no significant FRET between the I-II loop and C terminus in either dyspedic or dysgenic myotubes (e). The value of the I_Y*/I_C ratio in the absence of FRET (0.25, horizontal dashed line) was determined as the mean of the I_Y*/I_C quotients determined for the α_1S tandem in dyspedic and dysgenic myotubes (g).