A rhodopsin gene expressed in photoreceptor cell R7 of the Drosophila eye: homologies with other signal-transducing molecules.

We have isolated an opsin gene from D. melanogaster that is expressed in the ultraviolet-sensitive photoreceptor cell R7 of the Drosophila compound eye. This opsin gene contains no introns and encodes a 383 amino acid polypeptide that is approximately 35% homologous to the blue absorbing ninaE and Rh2 opsins, which are expressed in photoreceptor cells R1-6 and R8, respectively. Amino acid homologies between these different opsins and other signal-transducing molecules suggest an important role for the conserved domains of rhodopsin in the transduction of extracellular signals.