Characterization of lamprey rhodopsin by isolation from lamprey retina and expression in mammalian cells

A visual pigment was extracted from lamprey retina and was expressed in cultured mammalian cells (293S) using a cDNA fragment isolated from lamprey retina. The extracted pigment, a putative lamprey rhodopsin, had an absorption maximum at 503 nm. The recombinant lamprey rhodopsin, reconstituted with 11-cis-retinal, showed an absorption maximum at about 500 nm. Both pigments reacted with an anti-bovine rhodopsin antibody (Rh29), which recognizes the short photoreceptor cells in lamprey retina. Unlike rhodopsins of higher vertebrates, the lamprey rhodopsin bleached gradually in the presence of 100 mM hydroxylamine even in the dark. Our results suggest that, despite its high similarities with other vertebrate rhodopsins, lamprey rhodopsin has a character different from those of higher vertebrates.