Analogues of the Nicotinic Acid Adenine Dinucleotide Phosphate (NAADP) Antagonist Ned-19 Indicate Two Binding Sites on the NAADP Receptor

Rosen, Daniel, Lewis, Alexander M., Mizote, Akiko, Thomas, Justyn M., Aley, Parvinder K., Vasudevan, Sridhar R., Parkesh, Raman, Galione, Antony, Izumi, Minoru, Ganesan, A. and Churchill, Grant C. (2009) Analogues of the Nicotinic Acid Adenine Dinucleotide Phosphate (NAADP) Antagonist Ned-19 Indicate Two Binding Sites on the NAADP Receptor. Journal of Biological Chemistry, 284 (50). pp. 34930-34934. ISSN 0021-9258

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Abstract

Nicotinic acid adenine dinucleotide phosphate (NAADP) is a Ca2+-releasing messenger. Biological data suggest that its receptor has two binding sites: one high-affinity locking site and one low-affinity opening site. To directly address the presence and function of these putative binding sites, we synthesized and tested analogues of the NAADP antagonist Ned-19. Ned-19 itself inhibits both NAADP-mediated Ca2+ release and NAADP binding. A fluorometry bioassay was used to assess NAADP-mediated Ca2+ release, whereas a radioreceptor assay was used to assess binding to the NAADP receptor (only at the high-affinity site). In Ned-20, the fluorine is para rather than ortho as in Ned-19. Ned-20 does not inhibit NAADP-mediated Ca2+ release but inhibits NAADP binding. Conversely, Ned-19.4 (a methyl ester of Ned-19) inhibits NAADP-mediated Ca2+ release but cannot inhibit NAADP binding. Furthermore, Ned-20 prevents the self-desensitization response characteristic of NAADP in sea urchin eggs, confirming that this response is mediated by a high-affinity allosteric site to which NAADP binds in the radioreceptor assay. Collectively, these data provide the first direct evidence for two binding sites (one high- and one low-affinity) on the NAADP receptor.

Item Type: Article
Faculty \ School: Faculty of Science > School of Pharmacy
Depositing User: Users 2731 not found.
Date Deposited: 20 Oct 2011 10:52
Last Modified: 22 Apr 2020 14:17
URI: https://ueaeprints.uea.ac.uk/id/eprint/35109
DOI: 10.1074/jbc.M109.016519

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