Polarity of TRH receptors in transfected MDCK cells is independent of endocytosis signals and G protein coupling.
Am J Physiol
; 270(3 Pt 1): C753-62, 1996 Mar.
Article
em En
| MEDLINE
| ID: mdl-8638654
ABSTRACT
Information concerning the molecular sorting of G protein-coupled receptors in polarized epithelial cells is limited. Therefore, we have expressed the receptor for thyrotropin-releasing hormone (TRH) in Madin-Darby canine kidney (MDCK) cells by adenovirus-mediated gene transfer to determine its distribution in a model cell system and to begin analyzing the molecular information responsible for its distribution. Equilibrium binding of [methyl-3H]TRH to apical and basolateral surfaces of polarized MDCK cells reveals that TRH receptors are expressed predominantly (>80%) on the basolateral cell surface. Receptors undergo rapid endocytosis following agonist binding; up to 80% are internalized in 15 min. A mutant receptor missing the last 59 residues, C335Stop, is poorly internalized (<10%) but is nevertheless basolaterally expressed (>85%). A second mutant TRH receptor, delta218-263, lacks essentially all of the third intracellular loop and is not coupled to G proteins on binding agonist. This receptor internalizes TRH approximately half as efficiently as wild-type TRH receptors but is nevertheless strongly polarized to the basolateral surface (>90%). These results indicate that molecular sequences responsible for basolateral accumulation of TRH receptors can be segregated from signals for ligand-induced receptor endocytosis and coupling to heterotrimeric G proteins.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Transdução de Sinais
/
Receptores do Hormônio Liberador da Tireotropina
/
Proteínas de Ligação ao GTP
/
Endocitose
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
Am J Physiol
Ano de publicação:
1996
Tipo de documento:
Article
País de afiliação:
Estados Unidos