A cDNA clone encoding a cytochrome P-450 (P-450) isozyme was isolated from a mouse liver cDNA library. This P-450, designated CYP2C29, the first member of the mouse CYP2C subfamily to be reported, contained the complete coding region of 490 amino acid residues. The deduced amino acid sequence of CYP2C29 exhibited 83% identity with that of the rat CYP2C7 and had an N-terminal sequence identical to that of P-450 MUT-2, a microsomal aldehyde oxygenase. Two peptides, derived from BrCN cleavage of P-450 MUT-2, were also identical to the cDNA deduced protein of CYP2C29. These results indicate that CYP2C29 cDNA encodes P-450 MUT-2.