Rhodopsin, one of the proteins responsible for sensing light in the eye, is also important in the generation of photoreceptor cells--photoreceptors that lack rhodopsin degenerate. Chang and Ready managed to prevent photoreceptor degeneration in Drosophila lacking rhodopsin by expressing a constitutively active form of a Rho guanosine triphosphatase, Drac1. It appears that Drac1 organizes the actin cytoskeleton in the developing photoreceptor cells. Rhodopsin appears to play an additional role beyond sensory perception, in that it activates a signal transduction pathway to stimulate morphogenesis during development. Colley provides a perspective on the data.
Colley, N.J. (2000) Actin' up with Rac1. Science 290: 1902-1903. [Full Text]