Figure 1. [³H]S107 binding to SR vesicles.

(A) Time course of total, nonspecific and specific [³H]S107 binding to SR vesicles incubated with 0.2 µM [³H]S107 in 0.25 M KCl, 20 mM imidazole, pH 7.0, 50 µM free Ca²⁺ and protease inhibitors for 1 to 9 h at 24°C. Nonspecific binding was determined by measuring [³H]S107 binding to SR vesicles heat-inactivated for 10 min at 95°C. Data are the mean ± SD of 3 experiments. (B) Total, nonspecific and specific [³H]S107 binding to SR vesicles incubated with 0.1 µM [³H]S107 and 0.1 to 100 µM S107 as above for 7 h at 24°C. Nonspecific binding was determined as in A. Specific binding curve was obtained using four parameter logistic equation shown in Materials and Methods.