Synthesizes the second messengers cyclic ADP-ribose and nicotinate-adenine dinucleotide phosphate, the former a second messenger that elicits calcium release from intracellular stores. May be involved in pre-B-cell growth. H2O + NAD(+) = ADP-D-ribose + H(+) + nicotinamide Homodimer. Pancreatic islets, kidney, spleen, heart, thymus, intestine and salivary gland. Belongs to the ADP-ribosyl cyclase family.