Synthesizes cyclic ADP-ribose (cADPR), a second messenger for glucose-induced insulin secretion (Probable). Synthesizes the Ca(2+) mobilizer nicotinate-adenine dinucleotide phosphate, NAADP(+), from 2'-phospho-cADPR and nicotinic acid, as well as from NADP(+) and nicotinic acid. Also has cADPR hydrolase activity (By similarity).
Subcellular locations: Cell surface, Membrane