Partial agonism in a G Protein-coupled receptor: role of the retinal ring structure in rhodopsin activation.
J Biol Chem
; 280(40): 34259-67, 2005 Oct 07.
Article
em En
| MEDLINE
| ID: mdl-16027155
ABSTRACT
The visual process in rod cells is initiated by absorption of a photon in the rhodopsin retinal chromophore and consequent retinal cis/trans-isomerization. The ring structure of retinal is thought to be needed to transmit the photonic energy into conformational changes culminating in the active metarhodopsin II (Meta II) intermediate. Here, we demonstrate that cis-acyclic retinals, lacking four carbon atoms of the ring, can activate rhodopsin. Detailed analysis of the activation pathway showed that, although the photoproduct pathway is more complex, Meta II formed with almost normal kinetics. However, lack of the ring structure resulted in a low amount of Meta II and a fast decay of activity. We conclude that the main role of the ring structure is to maintain the active state, thus specifying a mechanism of activation by a partial agonist of the G protein-coupled receptor rhodopsin.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Retina
/
Rodopsina
/
Receptores Acoplados a Proteínas G
Limite:
Animals
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
2005
Tipo de documento:
Article
País de afiliação:
Alemanha