Click here to close Hello! We notice that you are using Internet Explorer, which is not supported by Echinobase and may cause the site to display incorrectly. We suggest using a current version of Chrome, FireFox, or Safari.
Echinobase
ECB-ART-42246
J Biol Chem 2012 Jan 20;2874:2296-307. doi: 10.1074/jbc.M111.305813.
Show Gene links Show Anatomy links

Photoaffinity labeling of nicotinic acid adenine dinucleotide phosphate (NAADP) targets in mammalian cells.

Lin-Moshier Y , Walseth TF , Churamani D , Davidson SM , Slama JT , Hooper R , Brailoiu E , Patel S , Marchant JS .


???displayArticle.abstract???
Nicotinic acid adenine dinucleotide phosphate (NAADP) is an agonist-generated second messenger that releases Ca(2+) from intracellular acidic Ca(2+) stores. Recent evidence has identified the two-pore channels (TPCs) within the endolysosomal system as NAADP-regulated Ca(2+) channels that release organellar Ca(2+) in response to NAADP. However, little is known about the mechanism coupling NAADP binding to calcium release. To identify the NAADP binding site, we employed a photoaffinity labeling method using a radioactive photoprobe based on 5-azido-NAADP ([(32)P-5N(3)]NAADP) that exhibits high affinity binding to NAADP receptors. In several systems that are widely used for studying NAADP-evoked Ca(2+) signaling, including sea urchin eggs, human cell lines (HEK293, SKBR3), and mouse pancreas, 5N(3)-NAADP selectively labeled low molecular weight sites that exhibited the diagnostic pharmacology of NAADP-sensitive Ca(2+) release. Surprisingly, we were unable to demonstrate labeling of endogenous, or overexpressed, TPCs. Furthermore, labeling of high affinity NAADP binding sites was preserved in pancreatic samples from TPC1 and TPC2 knock-out mice. These photolabeling data suggest that an accessory component within a larger TPC complex is responsible for binding NAADP that is unique from the core channel itself. This observation necessitates critical evaluation of current models of NAADP-triggered activation of the TPC family.

???displayArticle.pubmedLink??? 22117075
???displayArticle.pmcLink??? PMC3268391
???displayArticle.link??? J Biol Chem
???displayArticle.grants??? [+]

Genes referenced: LOC100887844 LOC100893907 LOC115919910 LOC574780 LOC576539 tpc2

References [+] :
Aarhus, ADP-ribosyl cyclase and CD38 catalyze the synthesis of a calcium-mobilizing metabolite from NADP. 1995, Pubmed