Identification of a new component of the agonist binding site of the nicotinic alpha 7 homooligomeric receptor.
J Biol Chem
; 270(20): 11749-52, 1995 May 19.
Article
em En
| MEDLINE
| ID: mdl-7744821
ABSTRACT
Tryptophan 54 of the alpha 7 neuronal nicotinic homooligomeric receptor is homologous to gamma-Trp-55 and delta-Trp-57 of non-alpha subunits of Torpedo receptor labeled by d-tubocurarine. This residue was mutated on the alpha 7-V201-5-hydroxytryptamine (5HT)3 homooligomeric chimera, which displays alpha 7 nicotinic pharmacology, and for which both equilibrium binding studies and electrophysiological recordings could be carried out in parallel. Replacement of Trp-54 by a Phe, Ala, or His causes a progressive decrease both in binding affinity and in responses (EC50 or IC50) for acetylcholine, nicotine, and dihydro-beta-erythroidine, without significant modification in alpha-Bgtx binding. Except for Gln-56, comparatively small effects are observed when the other residues of the 52-58 region are mutated into alanine. These data support the participation of Trp-54 to ligand binding, and provide evidence for a new "complementary component" of the alpha 7 nicotinic binding site, distinct from its three-loop "principal component," and homologous to the "non-alpha component" present on gamma and delta subunits.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Receptores Nicotínicos
Tipo de estudo:
Diagnostic_studies
Limite:
Animals
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
1995
Tipo de documento:
Article
País de afiliação:
França
País de publicação:
EEUU
/
ESTADOS UNIDOS
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ESTADOS UNIDOS DA AMERICA
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EUA
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UNITED STATES
/
UNITED STATES OF AMERICA
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US
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USA