Convergent mechanism underlying the acquisition of vertebrate scotopic vision.
J Biol Chem
; 300(4): 107175, 2024 Apr.
Article
en En
| MEDLINE
| ID: mdl-38499150
ABSTRACT
High sensitivity of scotopic vision (vision in dim light conditions) is achieved by the rods' low background noise, which is attributed to a much lower thermal activation rate (kth) of rhodopsin compared with cone pigments. Frogs and nocturnal geckos uniquely possess atypical rods containing noncanonical cone pigments that exhibit low kth, mimicking rhodopsin. Here, we investigated the convergent mechanism underlying the low kth of rhodopsins and noncanonical cone pigments. Our biochemical analysis revealed that the kth of canonical cone pigments depends on their absorption maximum (λmax). However, rhodopsin and noncanonical cone pigments showed a substantially lower kth than predicted from the λmax dependency. Given that the λmax is inversely proportional to the activation energy of the pigments in the Hinshelwood distribution-based model, our findings suggest that rhodopsin and noncanonical cone pigments have convergently acquired low frequency of spontaneous-activation attempts, including thermal fluctuations of the protein moiety, in the molecular evolutionary processes from canonical cone pigments, which contributes to highly sensitive scotopic vision.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Rodopsina
/
Evolución Molecular
/
Visión Nocturna
Límite:
Animals
Idioma:
En
Revista:
J Biol Chem
Año:
2024
Tipo del documento:
Article
País de afiliación:
Japón