The interaction of spermine with the ryanodine receptor from skeletal muscle

The effect of polyamines on ryanodine binding activity of junctional sarcoplasmic reticulum membranes is described. Spermine stimulated the binding of ryanodine to its receptor up to 5-fold, with half-maximal stimulation obtained with 3.5 mM. Spermidine and putrescine also stimulated ryanodine binding, but they were about 12-fold less potent. The degree of stimulation is dependent on the NaCl concentration present in the assay medium. Spermine has no effect on the Ca(2+)-dependency of ryanodine binding but it increases the ryanodine binding affinity (Kd) by about 5.6-fold. Both the rate of ryanodine association with, and dissociation from, its binding site were affected by spermine. Spermine also stimulates the photoaffinity labelling by 3-O-(4-benzoyl)benzoyl[alpha-32P]ATP ([alpha-32P]BzATP) of the ryanodine receptor, increasing the BzATP binding affinity. We suggest that the stimulatory effect of spermine on ryanodine binding is due to its specific interaction with the ryanodine receptor. This spermine interaction enabled us to develop a new, one-step, fast and with high yield method for the purification of ryanodine receptor (Shoshan-Barmatz, V. and Zarka, A. (1992) Biochem. J. 284, in press).