PROSITE documentation PDOC00081
Cytochrome P450 cysteine heme-iron ligand signature


Cytochrome P450's [1,2,3] are a group of enzymes involved in the oxidative metabolism of a high number of natural compounds (such as steroids, fatty acids, prostaglandins, leukotrienes, etc) as well as drugs, carcinogens and mutagens. Based on sequence similarities, P450's have been classified into about forty different families [4,5]. P450's are proteins of 400 to 530 amino acids; the only exception is Bacillus BM-3 (CYP102) which is a protein of 1048 residues that contains a N-terminal P450 domain followed by a reductase domain. P450's are heme proteins. A conserved cysteine residue in the C-terminal part of P450's is involved in binding the heme iron in the fifth coordination site. From a region around this residue, we developed a ten residue signature specific to P450's.


The term 'cytochrome' P450, while commonly used, is incorrect as P450 are not electron-transfer proteins; the appropriate name is P450 'heme- thiolate proteins'.

Expert(s) to contact by email:

Degtyarenko K.N.

Last update:

December 2004 / Pattern and text revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

CYTOCHROME_P450, PS00086; Cytochrome P450 cysteine heme-iron ligand signature  (PATTERN)


1AuthorsNebert D.W. Gonzalez F.J.
TitleP450 genes: structure, evolution, and regulation.
SourceAnnu. Rev. Biochem. 56:945-993(1987).
PubMed ID3304150

2AuthorsCoon M.J. Ding X.X. Pernecky S.J. Vaz A.D.
TitleCytochrome P450: progress and predictions.
SourceFASEB J. 6:669-673(1992).
PubMed ID1537454

3AuthorsGuengerich F.P.
TitleReactions and significance of cytochrome P-450 enzymes.
SourceJ. Biol. Chem. 266:10019-10022(1991).
PubMed ID2037557

4AuthorsNelson D.R. Kamataki T. Waxman D.J. Guengerich F.P. Estabrook R.W. Feyereisen R. Gonzalez F.J. Coon M.J. Gunsalus I.C. Gotoh O.
TitleThe P450 superfamily: update on new sequences, gene mapping, accession numbers, early trivial names of enzymes, and nomenclature.
SourceDNA Cell Biol. 12:1-51(1993).
PubMed ID7678494

5AuthorsDegtyarenko K.N. Archakov A.I.
TitleMolecular evolution of P450 superfamily and P450-containing monooxygenase systems.
SourceFEBS Lett. 332:1-8(1993).
PubMed ID8405421

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