[³H]S107 binding to SR vesicles.

SR vesicles with low and high Bmax of [3H]ryanodine binding were obtained as described in Materials and Methods. Bmax of [3H]ryanodine binding was obtained as shown in Fig. S2A. Shown are the amounts of [3H]ryanodine specifically bound to SR vesicles after 5 h at 24°C. Specific [3H]S107 binding to SR vesicles was determined at 44 µM [3H]S107 and indicated free Ca2+ concentration as described in Fig. S2B. Shown are the amounts of S107 specifically bound to SR vesicles after 9 h incubation at 24°C. Data are the mean ± SD of 3–6 determinations.