Phylogenetic and functional analyses of the cytochrome P450 family 4

► Monophyletic groups were found in most subfamilies but not CYP4B and CYP4T. ► CYP4A as a basal subfamily to CYP4X and CYP4Z. ► CYP4V clustered with invertebrate subfamilies. ► B, B′, J′, K′, K″ helices and the end of C-terminus were conserved regions. ► CYP4X was hypothesized to specialize in metabolism of long chain fatty acids.