A putative selectivity filter in the G-protein-coupled receptors for parathyroid hormone and secretion.
J Biol Chem
; 271(16): 9205-8, 1996 Apr 19.
Article
en En
| MEDLINE
| ID: mdl-8621578
The seven transmembrane segments (TMs) of many G-protein-coupled receptors (GPCRs) are thought to form a cavity into which cognate ligands insert, leading to receptor activation. Residues lining the cavity are often essential for optimal ligand binding and/or signal transduction. The present studies evaluated whether residues lining the cavity also contribute to specificity, using GPCRs for the polypeptides parathyroid hormone (PTH) and secretin as models. These ligands display no sequence homology with one another, and neither ligand cross-reacts with the other's receptor. However, mutation of a single amino acid in the second TM of the secretin receptor to the corresponding residue in the PTH receptor (N192I) resulted in a receptor that binds and signals in response to PTH. The reciprocal mutation in the PTH receptor (I234N) likewise unmasked responsiveness to secretin. Neither mutation significantly altered the response of the receptors to their own ligands. The results suggest a model of specificity wherein TM residues near the extracellular surface of the receptor function as a selectivity filter that restricts access of inappropriate ligands to an activation site in the transmembrane cavity.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Hormona Paratiroidea
/
Receptores de la Hormona Gastrointestinal
/
Secretina
/
Receptores de Hormona Paratiroidea
/
Proteínas de Unión al GTP
Límite:
Animals
Idioma:
En
Revista:
J Biol Chem
Año:
1996
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Estados Unidos