Meeting Abstract
Duplication of the photosensitive protein, opsin, is important for expanding visual and photosensory systems as it can provide the genetic foundation for adaptation. From our transcriptome data, we discovered four rhabdomeric (Gq-protein coupled or Gq-opsins) opsins expressed in the scallop, Argopecten irradians. Two of these were previously unrecognized. The four opsins appear to be the result of a series of gene duplication events in Bivalvia. We hypothesize that the four Gq-opsins have diverged since duplicating, and we test this hypothesis using genomic, bioinformatics, and protein-modeling approaches. We provide evidence that the four Gq-opsins 1) have dissimilar amino acid sequences, 2) differ in tertiary structure, and 3) vary in their spatial expression across tissues. Amino acid sequence comparisons between Gq-opsins showed overall percent identity values ranged from 41.3 to 64.6%, and key structural motifs differed in sequence composition. Protein homology modeling predicted four unique tertiary structures, with different amino acid residues interacting with the light-sensitive chromophore. Finally, gene expression data determined that Gq-opsins differ in spatial pattern and relative levels across photosensitive tissues, including the mantle and the eye.
