Nicotinic acid adenine dinucleotide phosphate: a new intracellular second messenger?

Abstract
Nicotinic acid adenine dinucleotide phosphate (NAADP) is one of the most potent stimulators of intracellular Ca2+release known to date. The role of the NAADP system in physiological processes is being extensively investigated at the present time. Exciting new discoveries in the last 5 years suggest that the NAADP-regulated system may have a significant role in intracellular Ca2+signaling. The NAADP receptor and its associated Ca2+pool have been hypothesized to be important in several physiological processes including fertilization, T cell activation, and pancreatic secretion. However, whether NAADP is a new second messenger or a tool for the discovery of a new Ca2+channel is still an unanswered question.