Calcium feedback to cGMP synthesis strongly attenuates single-photon responses driven by long rhodopsin lifetimes.
Neuron
; 76(2): 370-82, 2012 Oct 18.
Article
en En
| MEDLINE
| ID: mdl-23083739
ABSTRACT
Rod photoreceptors generate amplified, reproducible responses to single photons via a G protein signaling cascade. Surprisingly, genetic perturbations that dramatically alter the deactivation of the principal signal amplifier, the GPCR rhodopsin (R∗), do not much alter the amplitude of single-photon responses (SPRs). These same perturbations, when crossed into a line lacking calcium feedback regulation of cGMP synthesis, produced much larger alterations in SPR amplitudes. Analysis of SPRs from rods with and without feedback reveal that the consequences of trial-to-trial fluctuations in R∗ lifetime in normal rods are also dampened by feedback regulation of cGMP synthesis. Thus, calcium feedback trumps the mechanisms of R∗ deactivation in determining the SPR amplitude, attenuating responses arising from longer R∗ lifetimes to a greater extent than those arising from shorter ones. As a result, rod SPRs achieve a more stereotyped amplitude, a characteristic considered important for reliable transmission through the visual system.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Rodopsina
/
Transducción de Señal
/
Calcio
/
Células Fotorreceptoras Retinianas Bastones
/
GMP Cíclico
/
Retroalimentación Fisiológica
Tipo de estudio:
Health_economic_evaluation
Límite:
Animals
Idioma:
En
Revista:
Neuron
Asunto de la revista:
NEUROLOGIA
Año:
2012
Tipo del documento:
Article
País de afiliación:
Estados Unidos