NAADP: a universal Ca2+ trigger.
Cells possess multiple calcium ion (Ca2+) stores and multiple messenger molecules to mobilize them. These include d-myo-inositol 1,4,5-trisphosphate (IP(3)), cyclic adenosine diphosphoribose (cADPR), and the most recently identified Ca2+-mobilizing messenger, nicotinic acid adenine dinucleotide phosphate (NAADP), which acts on a wide spectrum of cells, from plant cells to mammalian cells. Accumulating evidence indicates that NAADP targets both acidic (lysosome-like) Ca2+ stores and endoplasmic reticular stores. Recent studies in invertebrate and mammalian cells suggest that NAADP provides an initiating Ca2+ signal, which is amplified by cADPR- or IP(3)-dependent mechanisms (or both) through Ca2+-induced Ca2+ release. Diverse stimuli activate a rapid rise of endogenous NAADP concentration, resulting in severalfold increases of NAADP over basal values within seconds. The enzyme CD38 can catalyze both the synthesis and hydrolysis of NAADP, making it ideal for effecting the rapid metabolism of NAADP. The crystal structure of CD38 and the structures of its various substrate complexes have now been determined, clarifying the mechanism of its multifunctional catalysis. We anticipate that these advances will lead to the unmasking of all the key components of the Ca2+ signaling pathway mediated by NAADP.
Guse
Andreas H
AH
The Calcium Signaling Group, Institute of Biochemistry and Molecular Biology I, Cellular Signal Transduction, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, D-20146 Hamburg, Germany. guse@uke.uni-hamburg.de
Lee
Hon Cheung
HC
D051997:ADP-ribosyl Cyclase 1 / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D006801:Humans; D009249:NADP / Q000031:analogs & derivatives* / Q000502:physiology
D009249:NADP; C024376:NAADP; D051997:ADP-ribosyl Cyclase 1; D002118:Calcium