Fig. 2.

Ca²⁺-dependent activities of MH/CNM-associated RyR1 mutants. Ca²⁺-dependent changes in the activities of wild-type (WT) and mutant RyR1 were determined by the [³H]ryanodine binding method. Activities of mutant RyR1s carrying disease-associated mutations in EF-hand domain (A), S2–S3 loop (B), and S4–S5 loop (C) are shown together with that of WT-RyR1 (dotted line, mean values). A dashed line in B represents a mean value of WT-RyR2. D: IC₅₀ values of wild-type and mutant RyRs. E: activities at 40 nM free Ca²⁺ were normalized to the peak activities for wild-type and each mutant RyR1. *P < 0.05 compared with WT-RyR1 by one-way ANOVA followed by Tukey's test among 10 sample groups (wild-type and mutant RyR1s). Data are shown as means ± SE (n = 4–7).