Abstract
Most vertebrates have two types of photoreceptor neurons, rods and cones. Rods operate in dim light, whereas cones function in bright light. Cones have a lower photosensitivity and faster photoresponse kinetics when compared with those of rods. We have focused on opsin kinases (GRKs) responsible for deactivation of photoactivated opsins. We found that cone GRK has much higher activity than rod GRK in zebrafish. We also showed that ectopic expression of cone GRK in zebrafish rods leads to lowered photosensitivity. We also review recent topics on the molecular mechanisms underlying the rod-cone difference.
