C-terminal fusion of eGFP to the bradykinin B2 receptor strongly affects down-regulation but not receptor internalization or signaling.
Biol Chem
; 387(5): 603-10, 2006 May.
Article
em En
| MEDLINE
| ID: mdl-16740132
ABSTRACT
A functional comparison was made between the wild-type bradykinin B2 receptor (B2wt) and the chimera B2eGFP (enhanced green-fluorescent protein fused to the C-terminus of B2wt), both stably expressed in HEK 293 cells. There was almost no difference in terms of ligand-inducible receptor phosphorylation and internalization, signal transduction (accumulation of inositol phosphates) or expression and affinity. However, stimulation for up to 8 h with 10 microM bradykinin (BK) resulted in a strong decrease in surface receptors (by 60% within 5 h) in B2wt, but not in B2eGFP. When the expression levels of both constructs where comparably reduced using a weaker promoter, long-term stimulation resulted in a reduction in surface receptors for B2wt(low) to less than 20% within 1 h, whereas the chimera B2eGFP(low) still displayed 50% binding activity after 2 h. A 1-h incubation in the absence of BK resulted in a recovery of 60% of the binding in B2wt(low) after 1-h stimulation with BK, but of only 20% after 7-h stimulation. In contrast, B2eGFP(low) levels were restored to more than 70%, even after 7-h stimulation. These data indicate that although the fusion of eGFP to B2wt does not affect its ligand-induced internalization, it strongly reduces the down-regulation, most likely by promoting receptor recycling over degradation.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas Recombinantes de Fusão
/
Transdução de Sinais
/
Receptor B2 da Bradicinina
/
Proteínas de Fluorescência Verde
Limite:
Humans
Idioma:
En
Revista:
Biol Chem
Assunto da revista:
BIOQUIMICA
Ano de publicação:
2006
Tipo de documento:
Article
País de afiliação:
Alemanha