Cyclic ADP-ribose and calcium signaling in eggs

Cyclic ADP-ribose is a cyclic nucleotide with Ca2+ signaling functions. It was first discovered in sea urchin eggs and has since been shown to be active in a variety of cells. Another Ca2+ release mechanism recently described in the eggs is mediated by nicotinic acid dinucleotide phosphate, a derivative of NADP(+). This article summarizes current results on these two novel Ca2+-mobilizing pathways that are independent of inositol trisphosphate.