Synthesis and characterization of cyclic ATP-ribose: a potent mediator of calcium release

Cyclic ATP-ribose, synthesized by a combination of chemical and enzymatic methods, was twenty times more potent than cADPR in inducing Ca2+ release from rat brain microsomes. It induced Ca2+ release from the same Ca2+ stores as that of cADPR, but different from those of IP3 and cyclic ADP-ribose-phosphate.