Molecular cloning of a peroxidase mRNA specifically expressed in the ink gland of Sepia officinalis.

A full-length cDNA encoding a peroxidase has been assembled from two different overlapping cDNA clones isolated from the cDNA library of Sepia officinalis ink gland and 5' RACE procedure. The cDNA of 2898 bp contains an open reading frame of 2778 bp corresponding to a protein of 926 amino acids. The protein shows 76% identity with a peroxidase isolated from the light organ of the squid Euprymna scolopes and approximately 30% identity with mammalian peroxidases. Northern blot analysis of mRNA from various tissues of Sepia officinalis reveals that peroxidase is exclusively expressed in the ink gland. These results represent the first characterization of a melanogenic peroxidase whose possible involvement in the biosynthesis of melanin is discussed.