Structural requirements for the activation of the human growth hormone secretagogue receptor by peptide and nonpeptide secretagogues.
Mol Endocrinol
; 12(1): 137-45, 1998 Jan.
Article
em En
| MEDLINE
| ID: mdl-9440817
ABSTRACT
Antibodies raised against an intracellular and extracellular domain of the GH secretagogue receptor (GHS-R) confirmed that its topological orientation in the lipid bilayer is as predicted for G protein-coupled receptors with seven transmembrane domains. A strategy for mapping the agonist-binding site of the human GHS-R was conceived based on our understanding of ligand binding in biogenic amine and peptide hormone G protein-coupled receptors. Using site-directed mutagenesis and molecular modeling, we classified GHS peptide and nonpeptide agonist binding in the context of its receptor environment. All peptide and nonpeptide ligand classes shared a common binding domain in transmembrane (TM) region 3 of the GHS-R. This finding was based on TM-3 mutation E124Q, which eliminated the counter-ion to the shared basic N+ group of all GHSs and resulted in a nonfunctional receptor. Restoration of function for the E124Q mutant was achieved by a complementary change in the MK-0677 ligand through modification of its amine side-chain to the corresponding alcohol. Contacts in other TM domains [TM-2 (D99N), TM-5 (M213K, S117A), TM-6 (H280F), and extracellular loop 1 (C116A)] of the receptor revealed specificity for the different peptide, benzolactam, and spiroindolane GHSs. GHS-R agonism, therefore, does not require identical disposition of all agonist classes at the ligand-binding site. Our results support the hypothesis that the ligand-binding pocket in the GHS-R is spatially disposed similarly to the well characterized catechol-binding site in the beta2-adrenergic receptor.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Peptídeos
/
Receptores de Superfície Celular
/
Hormônio do Crescimento Humano
/
Proteínas de Ligação ao GTP
/
Receptores Acoplados a Proteínas G
Tipo de estudo:
Prognostic_studies
Limite:
Animals
/
Humans
Idioma:
En
Revista:
Mol Endocrinol
Assunto da revista:
BIOLOGIA MOLECULAR
/
ENDOCRINOLOGIA
Ano de publicação:
1998
Tipo de documento:
Article
País de afiliação:
Estados Unidos