Disclosed is a novel photo-activatable derivative of ryanodine 9-hydroxy-21-(4-azidobenzoyloxy)-9-epiryanodine. This novel ryanodine derivative has been conjugated to keyhole limpet hemocyanin (KLH) and used for the production of antibodies with high affinity and specificity to ryanodine. A radioimmunoassay specific for ryanodine was developed using the anti-ryanodine antibodies, and a dissociation constant for ryanodine of 1 nM was determined. Also disclosed is the binding of a labeled, photoactivatable derivative of ryanodine (ABRy) with the ryanodine receptor of skeletal, cardiac and brain membranes. Digestion of the labeled ryanodine receptor revealed a labeled 76 kDa tryptic fragment which is critical for the formation of the high affinity ryanodine binding site.