Figure 4. Unaltered regulation by FKBP12 in RyR1_MHS.

(A) Binding of FKBP12 to RyR1. CHAPS-solubilized SR proteins from normal (left-hand panel) and MHS (right-hand panel) pigs were immunoprecipitated with anti-RyR1 antibody in the presence (+) and absence (−) of 10 μM FK506. RyR1 and FKBP12 in the precipitate were detected by Western blotting. A similar amount of FKBP12 was co-precipitated with RyR1_N and RyR1_MHS. FK506 at 10 μM (+FK506) completely prevented the FKBP12 binding. (B) Effect of FK506 on [³H]ryanodine binding. Experiments were carried out as described in Figure 2 at 30 μM Ca²⁺ with (closed bars) and without (open bars) 10 μM FK506. The 100% values for RyR1_N and RyR1_MHS were 0.013 and 0.13 in B/B_max respectively. Results are means±S.E.M. (n=3). *P<0.05.