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

Rosen, D, Lewis, AM, Mizote, A, Thomas, JM, Aley, PK, Vasudevan, SR, Parkesh, R, Galione, A, Izumi, M, Ganesan, A and Churchill, GC (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
University of East Anglia > Faculty of Science > Research Groups > Medicinal Chemistry
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Depositing User: Deborah Clemitshaw
Date Deposited: 20 Oct 2011 11:52
Last Modified: 25 Jul 2018 04:36
URI: https://ueaeprints.uea.ac.uk/id/eprint/35109
DOI: 10.1074/jbc.M109.016519

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