Vogalis, F., Shiraki, T., Kojima, D., Wada, Y., Nishiwaki, Y., Jarvinen, J.L., Sugiyama, J., Kawakami, K., Masai, I., Kawamura, S., Fukada, Y., and Lamb,T.D. (2011) Ectopic expression of cone-specific G-protein-coupled receptor kinase GRK7 in zebrafish rods leads to lower photosensitivity and altered responses. The Journal of physiology. 589(9):2321-2348.
Non-technical summary When rod and cone photoreceptors in the eye respond to light, they need to recover, and the first step in recovery involves a protein called G-protein receptor kinase (GRK). Rods, which underlie night vision, employ a variant called GRK1, whereas cones, which mediate day vision, typically employ a variant called GRK7. We have engineered rod cells in the zebrafish retina that additionally express the cone variant, GRK7. By recording electrically from these modified rods, we have found that they are less sensitive to light than normal rods, in that regard mimicking cones. We have also found evidence to suggest that the size of the cell's response to a single photon (the smallest particle of light) is normal when recovery is mediated by GRK1, but is small (and hence somewhat cone-like) when mediated by GRK7. These results help us understand the differences between rod and cone photoreceptors.