Cloning and sequencing of cytochrome P450 2X1 from channel catfish (Ictalurus punctatus)

Previous purification and immunochemical studies in livers of channel catfish indicated the presence of at least four cytochrome P450 (CYP) 2-like isoforms. Sequencing of the first 18 amino acids of one purified form indicated a CYP2 isoform. From this N-terminal sequence and other published CYP2 sequences from fish, primers were designed and a full-length CYP cDNA was identified from reverse-transcribed catfish liver mRNA. 5′ and 3′ RACE was used to obtain an open reading frame of 1470 bp encoding a 490 amino acid protein (approximately 57 kD). CYP2X1 was most identical to Fundulus heteroclitus CYP2P2 (41%); CYP2N2 (40%): and CYP2N1 (39%).