[Expression of cytochrome P-450 genes].

Cytochromes P-450 are important in the oxidative metabolism of many endogenous substrates, as well as innumerable drugs, chemical carcinogens, and environmental pollutants. Biochemical analyses of cytochrome P-450 have revealed multiple isoenzymes. Information for synthesis of these isoenzymes is contained in different genes. Based on the degree of relatedness in DNA sequence, the genes for cytochrome P-450 have been classified into different families, constituting cytochrome P-450 multigene superfamily. Particular chemicals induce expression of one or more genes belonging to definite cytochrome P-450 family. Expression of these genes may have served as a mechanism by which the cell respond to specific chemical signals (xenobiotic or hormonal).