CD38 has both ADP-ribosyl cyclase and cADPR hydrolase activities and is capable of cleaving nicotinamide adenine dinucleotide (NAD) to cyclic ADP ribose (cADPR) which is a trigger for intracellular [Ca.sup.2+] release and hydrolyzing cADPR to
ADPR, respectively [3].
The CD38 gene encodes a glycosylated ~45 kDa type II transmembrane protein whose enzymatic activity generates cADPR and adenosine diphosphoribose (
ADPR) from [NAD.sup.+] and nicotinic acid adenine dinucleotide phosphate (NAADP) from [NADP.sup.+].
CD38 is simultaneously a receptor and adhesion molecule as well as an ectoenzyme that catalyses the synthesis of ADP ribose (
ADPR), cyclic
ADPR (cAdPR), and nicotinic acid adenine dinucleotide phosphate (NAADP), starting from nicotinamide adenine dinucleotide ([NAD.sup.+]).