The sequence of squid (Loligo forbesi) rhodopsin was determined by protein and cDNA sequencing. The protein has close similarity to octopus rhodopsin, having an N-terminal region (residues 1-340) which resembles other guanine-nucleotide-binding protein (G-protein)-linked receptors and a repetitive proline-rich C-terminus (residues 340-452). Comparison of the sequence of squid rhodopsin with those of other members of the G-protein-linked receptor superfamily reveals features which we predict to have both structural and functional importance.
