Specificity of the cytochrome P‐450 interaction with cytochromeb5

Abstract
The specificity of the interaction of cytochromeb 5 with different forms of cytochrome P‐450 was examined. Immunopurification of cytochromes P‐450 1A1, 2B1 and 2E1 from rat liver microsomes resulted in co‐purification of cytochromeb 5 with cytochrome P‐450 forms 2B1 and 2EI but not 1A1. This specificity was evaluated in conjunction with multiple sequence alignment of the three cytochrome P‐450s and a molecular model of the cytochrome P‐450‐cytochromeb 5 complex [(1989) Biochemistry 28, 8201–8205]. These analyses suggest two basic residues in the arginine cluster region of P‐450, which are present in P‐450s 2B1 and 2E1 but are absent in P‐450 1A1, as potential binding sites for cytochromeb 5.