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This laboratory previously expressed cDNAs encoding rabbit liver cytochrome P450 2E1. (the ethanol-inducible isoform) and the corresponding protein lacking amino acids 3-29, a proposed membrane anchor, in Escherichia coli. Unexpectedly, the shortened protein, like the full-length form, was found to be predominantly located in the bacterial inner membrane rather than the cytosol and to have full catalytic activity. Additional proteins with alterations in the NH₂-terminal region of P450 2E1 or P450 2B4 (the phenobarbital-inducible isoform) were similarly expressed, and it was concluded that such modifications can change the cytochrome to an increased cytosolic localization and that the first two hydrophobic segments are not uniquely involved in attachment to the bacterial membrane (Pernecky et al., 1993, Proc. Natl. Acad. Sci. USA 90, 2651-2655). In the present study, three chimeric cytochromes were produced …