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. Expressed in the bone marrow, spleen and thymus in lymphoid organs, and the lung, kidney and heart in non-lymphoid organs. Belongs to the ADP-ribosyl cyclase family.