Cytochrome P-450 in the housefly: induction, substrate specificity and comparison to three rat hepatic isoenzymes

1. Both phenobarbital and clofibrate pretreatment cause a qualitative change in cytochrome P-450 content in housefly (Musca domestica). Based on changes in substrate specificity, both inducing agents appear to cause induction of an isoenzyme (or group of isoenzymes) of cytochrome P-450 in housefly, and this response is similar in extent and effect to that described in rodents. 2. Using Western blot analysis and probing with antibodies to three rat hepatic isoenzymes (P450 IA1, P450 IIB1 and P450 IVA1), common structural epitopes with housefly cytochrome P-450 were sought. Despite similarities in patterns of induction and catalytic function, little evidence for structural commonality between the cytochrome P-450 in rat and housefly was observed.