Genetic analyses of the green visual pigments of rabbit (Oryctolagus cuniculus) and rat (Rattus norvegicus).

We have cloned and sequenced the green opsin genes of rabbit and rat. When these genes are expressed in cultured cells and reconstituted with 11-cis retinal, the resulting visual pigments have wavelengths of maximal absorption (lambdamax) of 509nm. These blue-shifted lambdamax values are fully explained by their aa composition A, Y, Y, T, and S at sites 180, 197, 277, 285, and 308, respectively. The inference on the ancestral pigment sequences strongly suggests that the rabbit and rat (and mouse) green pigments attained the extant lambdamax values independently, mainly by the single aa replacement A308S.