Cytochrome P450 1A1 and Cytochrome P450 1A2 (CYP1A1 (for Cytochrome P450 1A1), CYP1A2 (for Cytochrome P450 1A2))

Cytochrome P450 1A1 and Cytochrome P450 1A2 are closely related monooxygenase enzymes belonging to the cytochrome P450 superfamily. They play key roles in the metabolism of drugs, endogenous compounds, and environmental toxins. CYP1A1 is predominantly extrahepatic and well-known for its ability to convert polycyclic aromatic hydrocarbons (from sources such as tobacco smoke) into active carcinogenic metabolites, thus playing a major role in chemical carcinogenesis. CYP1A2 is primarily hepatic and responsible for the metabolism of various drugs (caffeine, theophylline, tacrine, phenacetin), and endogenous compounds such as fatty acids and steroid hormones. Both CYP1A1 and CYP1A2 are common therapeutic targets for drug development and toxicity studies; their expression and activity can be induced or inhibited by various drugs and xenobiotics, and genetic variation contributes to individual differences in drug response and cancer risk. They share high sequence homology, but differ in tissue distribution and substrate specificity. Both are encoded by adjacent genes (CYP1A1 and CYP1A2) on chromosome 15q24.1.

Other names

CYP1A1Cytochrome P450 1A1CYP1A2Cytochrome P450 1A2

Substrate oxidation/hydroxylation via monooxygenase activity, introducing an oxygen atom into the substrate; Drug metabolism (phase-I metabolic transformation); Bioactivation of procarcinogens (especially CYP1A1); Competitive or mechanism-based inhibition (e.g., by drugs or inhibitors described above)