Extended Data Fig. 3: Kinetic model for the photoconversion and regeneration of rho in disc membranes.
From: Capturing a rhodopsin receptor signalling cascade across a native membrane
The photoconversion and regeneration processes involve a number of reactions outlined above. To simplify our kinetic model, we have divided the light response process into three phases. a, First, < 18 s when a rapid increase of rho is observed, prior to a steady decrease. b, This initial fast reaction 0 –18 s is attributed to the rapid regeneration of cis- retinal rho competing with photoconversion (rho → ops). Dark-adapted membranes possess N-ret-PE which responds rapidly to light such N-all-trans-ret-PE is activated and dissociates into cis-retinal and PE. Regenerated cis-retinal is then able to interact with opsin to form cis-retinal rho. Concurrently, existing cis-retinal rho photoconverts to active rho* and then deactivated opsin. c, During the second phase (> 18 s), after the original N-ret-PE is consumed, isomerization of cis-retinal rho to rho* continues with minimal regeneration of cis-retinal rho. rho* hydrolyses into opsin and all-trans-retinal. (Supplementary Notes).
