Analogues of the nicotinic acid adenine dinucleotide phosphate (NAADP) antagonist Ned-19 indicate two binding sites on the NAADP receptor.
J Biol Chem
; 284(50): 34930-4, 2009 Dec 11.
Article
em En
| MEDLINE
| ID: mdl-19826006
ABSTRACT
Nicotinic acid adenine dinucleotide phosphate (NAADP) is a Ca(2+)-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 Ca(2+) release and NAADP binding. A fluorometry bioassay was used to assess NAADP-mediated Ca(2+) 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 Ca(2+) release but inhibits NAADP binding. Conversely, Ned-19.4 (a methyl ester of Ned-19) inhibits NAADP-mediated Ca(2+) 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.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Piperazinas
/
Carbolinas
/
Receptores de Superfície Celular
/
NADP
Limite:
Animals
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
2009
Tipo de documento:
Article
País de afiliação:
Reino Unido