Cloning and characterization of the pineal gland-specific opsin gene of marine lamprey (Petromyzon marinus)

We have cloned and sequenced the pineal gland-specific opsin (P opsin) gene, p(Pm), Of marine lamprey, P. marinus. The deduced P opsin, P-Pm, consisting of 444 aa, is about 90 aa longer than the orthologous opsins of chicken, pigeon, and American chameleon. The evolution of P-Pm is characterized not only by a significantly higher rate of aa replacement than the other P opsins but also by a larger number of unique aa replacements at highly conserved sites in the nonTM region. These changes in P-Pm might have been important in achieving marine lamprey-specific interaction between P-Pm and other proteins in the pineal gland. (C) 1997 Elsevier Science B.V.