Rod & cone photoreceptors and ABCA4 mechanism in OS disc membranes

Rod & cone photoreceptors and ABCA4 mechanism in OS disc membranes: In both rod and cone cells, the light-sensitive OS is attached to the inner segment (IS) by a connecting cilium (CC). Rhodopsin, the visual pigment in rod cells, comprises the protein opsin bound to the chromophore 11-cis-retinal, which is isomerized to all-trans-retinal upon photon absorption. Once released from opsin, all-trans-retinal then reacts with PE to form a Schiff base. ABCA4 then “flips” all-trans-retinal to the outer portion of the disc membrane to access the visual cycle. | Sears, A. E., Bernstein, P. S., Cideciyan, A. V., Hoyng, C., Charbel Issa, P., Palczewski, K., Rosenfeld, P. J., Sadda, S., Schraermeyer, U., Sparrow, J. R., Washington, I., & Scholl, H. (2017). Towards Treatment of Stargardt Disease: Workshop Organized and Sponsored by the Foundation Fighting Blindness. Translational vision science & technology, 6(5), 6. https://doi.org/10.1167/tvst.6.5.6