Like night and day: rods and cones have different pigment regeneration pathways.

Sustained vision requires continuous regeneration of visual pigments in rod and cone photoreceptors by the 11-cis-retinal chromophore. In this issue of Neuron, Mata et al. report a novel enzymatic pathway uniquely designed to keep up with the high demand for cone pigment regeneration in bright light and to preclude rods from utilizing chromophore produced in daylight, when rods are not very useful for vision.