Figure 5.

Dose-dependent activation of [³H]-ryanodine binding by native IpTxa and Alexa-IpTxa. Skeletal SR vesicles were incubated with 7 nM [³H]ryanodine in the absence (control 100%) and the indicated concentration of native (B) or modified IpTxa (A) The binding reaction was carried out for 90 min at 36˚C in medium containing 0.2 M KCl, 10 mM Na-HEPES (pH 7.2) and 10 μM CaCl₂. Free and bound ligand were separated by rapid filtration as described in methods. Results are the mean ± S.D. of n=4 independent experiments.