Fig. 1. Mapping of P450MT2 domains needed for binding to Adx and CPR by using the mammalian two-hybrid system. (A) The N-terminal deletions of P4501A1 and the location of sequences showing partial identity to the conserved Adx-binding domain of P450c27. (B) The level of CAT protein indicating the extent of interaction between the various 1A1 deletion proteins and Adx or CPR proteins expressedin COS cells. The details of mammalian two-hybrid screening, transfection and measurement of CAT protein by ELISA are given in Materials and methods.