Implications of dimeric activation of PDE6 for rod phototransduction.
Open Biol
; 8(8)2018 08.
Article
em En
| MEDLINE
| ID: mdl-30068567
ABSTRACT
We examine the implications of a recent report providing evidence that two transducins must bind to the rod phosphodiesterase to elicit significant hydrolytic activity. To predict the rod photoreceptor's electrical response, we use numerical simulation of the two-dimensional diffusional contact of interacting molecules at the surface of the disc membrane, and then we use the simulated PDE activity as the driving function for the downstream reaction cascade. The results account for a number of aspects of rod phototransduction that have previously been puzzling. For example, they explain the existence of a greater initial delay in rods than in cones. Furthermore, our analysis suggests that the 'continuous' noise recorded in rods in darkness is likely to arise from spontaneous activation of individual molecules of PDE at a rate of a few tens per second per rod, probably as a consequence of spontaneous activation of transducins at a rate of thousands per second per rod. Hence, the dimeric activation of PDE in rods provides immunity against spontaneous transducin activation, thereby reducing the continuous noise. Our analysis also provides a coherent quantitative explanation of the amplification underlying the single photon response. Overall, numerical analysis of the dimeric activation of PDE places rod phototransduction in a new light.
Palavras-chave
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Células Fotorreceptoras Retinianas Bastonetes
/
Nucleotídeo Cíclico Fosfodiesterase do Tipo 6
/
Transdução de Sinal Luminoso
Tipo de estudo:
Prognostic_studies
Limite:
Animals
/
Humans
Idioma:
En
Revista:
Open Biol
Ano de publicação:
2018
Tipo de documento:
Article
País de afiliação:
Austrália