Comparative studies on the late bleaching processes of four kinds of cone visual pigments and rod visual pigment.
Biochemistry
; 51(21): 4300-8, 2012 May 29.
Article
en En
| MEDLINE
| ID: mdl-22571736
Visual pigments in rod and cone photoreceptor cells of vertebrate retinas are highly diversified photoreceptive proteins that consist of a protein moiety opsin and a light-absorbing chromophore 11-cis-retinal. There are four types of cone visual pigments and a single type of rod visual pigment. The reaction process of the rod visual pigment, rhodopsin, has been extensively investigated, whereas there have been few studies of cone visual pigments. Here we comprehensively investigated the reaction processes of cone visual pigments on a time scale of milliseconds to minutes, using flash photolysis equipment optimized for cone visual pigment photochemistry. We used chicken violet (L-group), chicken blue (M1-group), chicken green (M2-group), and monkey green (L-group) visual pigments as representatives of the respective groups of the phylogenetic tree of cone pigments. The S, M1, and M2 pigments showed the formation of a pH-dependent mixture of meta intermediates, similar to that formed from rhodopsin. Although monkey green (L-group) also formed a mixture of meta intermediates, pH dependency of meta intermediates was not observed. However, meta intermediates of monkey green became pH dependent when the chloride ion bound to the monkey green was replaced with a nitrate ion. These results strongly suggest that rhodopsin and S, M1, and M2 cone visual pigments share a molecular mechanism for activation, whereas the L-group pigment may have a special reaction mechanism involving the chloride-binding site.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Pigmentos Retinianos
/
Células Fotorreceptoras Retinianas Bastones
/
Células Fotorreceptoras Retinianas Conos
/
Fotoblanqueo
Límite:
Animals
Idioma:
En
Revista:
Biochemistry
Año:
2012
Tipo del documento:
Article
País de afiliación:
Japón
Pais de publicación:
Estados Unidos