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2175  structures 5038  species 0  interactions 213489  sequences 2142  architectures

Family: p450 (PF00067)

Summary: Cytochrome P450

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This is the Wikipedia entry entitled "Cytochrome P450". More...

Cytochrome P450 Edit Wikipedia article

Cytochrome P450

Cytochrome P450 is a generic term used to describe a class of enzymes which catalyze the oxidative metabolism of a variety of compounds. In most animals, including humans, hepatic cytochrome P450s are the most widely studied of the P450 enzymes.

The term cytochrome P450 refers to the fact that these enzymes have a light absorbtion peak at 450 nm when bound to Carbon Monoxide.

Genes for the P450 enzymes are labelled with the abbreviation CYP, followed by an Arabic number indicating the gene family, a capital letter indicating the subfamily, and an Arabic number for the individual gene. For example, CYP2E1 is the designation given to the gene responsible for ethanol metabolism.

This page is based on a Wikipedia article. The text is available under the Creative Commons Attribution/Share-Alike License.

This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.

Cytochrome P450 Provide feedback

Cytochrome P450s are haem-thiolate proteins [6] involved in the oxidative degradation of various compounds. They are particularly well known for their role in the degradation of environmental toxins and mutagens. They can be divided into 4 classes, according to the method by which electrons from NAD(P)H are delivered to the catalytic site. Sequence conservation is relatively low within the family - there are only 3 absolutely conserved residues - but their general topography and structural fold are highly conserved. The conserved core is composed of a coil termed the 'meander', a four-helix bundle, helices J and K, and two sets of beta-sheets. These constitute the haem-binding loop (with an absolutely conserved cysteine that serves as the 5th ligand for the haem iron), the proton-transfer groove and the absolutely conserved EXXR motif in helix K. While prokaryotic P450s are soluble proteins, most eukaryotic P450s are associated with microsomal membranes. their general enzymatic function is to catalyse regiospecific and stereospecific oxidation of non-activated hydrocarbons at physiological temperatures [6].

Literature references

  1. Graham-Lorence S, Amarneh B, White RE, Peterson JA, Simpson ER; , Protein Sci 1995;4:1065-1080.: A three-dimensional model of aromatase cytochrome P450. PUBMED:7549871 EPMC:7549871

  2. Degtyarenko KN, Archakov AI; , FEBS Lett 1993;332:1-8.: Molecular evolution of P450 superfamily and P450-containing monooxygenase systems. PUBMED:8405421 EPMC:8405421

  3. Nelson DR, Kamataki T, Waxman DJ, Guengerich FP, Estabrook RW, Feyereisen R, Gonzalez FJ, Coon MJ, Gunsalus IC, Gotoh O, et al; , DNA Cell Biol 1993;12:1-51.: The P450 superfamily: update on new sequences, gene mapping, accession numbers, early trivial names of enzymes, and nomenclature. PUBMED:7678494 EPMC:7678494

  4. Guengerich FP; , J Biol Chem 1991;266:10019-10022.: Reactions and significance of cytochrome P-450 enzymes. PUBMED:2037557 EPMC:2037557

  5. Nebert DW, Gonzalez FJ; , Annu Rev Biochem 1987;56:945-993.: P450 genes: structure, evolution, and regulation. PUBMED:3304150 EPMC:3304150

  6. Werck-Reichhart D, Feyereisen R; , Genome Biol 2000;1:REVIEWS3003.: Cytochromes P450: a success story. PUBMED:11178272 EPMC:11178272

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR001128

Cytochrome P450 enzymes are a superfamily of haem-containing mono-oxygenases that are found in all kingdoms of life, and which show extraordinary diversity in their reaction chemistry. In mammals, these proteins are found primarily in microsomes of hepatocytes and other cell types, where they oxidise steroids, fatty acids and xenobiotics, and are important for the detoxification and clearance of various compounds, as well as for hormone synthesis and breakdown, cholesterol synthesis and vitamin D metabolism. In plants, these proteins are important for the biosynthesis of several compounds such as hormones, defensive compounds and fatty acids. In bacteria, they are important for several metabolic processes, such as the biosynthesis of antibiotic erythromycin in Saccharopolyspora erythraea (Streptomyces erythraeus).

Cytochrome P450 enzymes use haem to oxidise their substrates, using protons derived from NADH or NADPH to split the oxygen so a single atom can be added to a substrate. They also require electrons, which they receive from a variety of redox partners. In certain cases, cytochrome P450 can be fused to its redox partner to produce a bi-functional protein, such as with P450BM-3 from Bacillus megaterium [ PUBMED:17023115 ], which has haem and flavin domains.

Organisms produce many different cytochrome P450 enzymes (at least 58 in humans), which together with alternative splicing can provide a wide array of enzymes with different substrate and tissue specificities. Individual cytochrome P450 proteins follow the nomenclature: CYP, followed by a number (family), then a letter (subfamily), and another number (protein); e.g. CYP3A4 is the fourth protein in family 3, subfamily A. In general, family members should share >40% identity, while subfamily members should share >55% identity.

Cytochrome P450 proteins can also be grouped by two different schemes. One scheme was based on a taxonomic split: class I (prokaryotic/mitochondrial) and class II (eukaryotic microsomes). The other scheme was based on the number of components in the system: class B (3-components) and class E (2-components). These classes merge to a certain degree. Most prokaryotes and mitochondria (and fungal CYP55) have 3-component systems (class I/class B) - a FAD-containing flavoprotein (NAD(P)H-dependent reductase), an iron-sulphur protein and P450. Most eukaryotic microsomes have 2-component systems (class II/class E) - NADPH:P450 reductase (FAD and FMN-containing flavoprotein) and P450. There are exceptions to this scheme, such as 1-component systems that resemble class E enzymes [ PUBMED:16042601 , PUBMED:15128046 , PUBMED:8637843 ]. The class E enzymes can be further subdivided into five sequence clusters, groups I-V, each of which may contain more than one cytochrome P450 family (eg, CYP1 and CYP2 are both found in group I). The divergence of the cytochrome P450 superfamily into B- and E-classes, and further divergence into stable clusters within the E-class, appears to be very ancient, occurring before the appearance of eukaryotes.

This family also includes germacrene A hydroxylase (GAO1; EC ) from plants such as lettuce (Lactuca sativa). GAO1 is required for the biosynthesis of germacrene-derived sesquiterpene lactones, which are characteristic natural products in members of the Asteraceae [ PUBMED:20351109 ].

Gene Ontology

The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.

Domain organisation

Below is a listing of the unique domain organisations or architectures in which this domain is found. More...

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We store a range of different sequence alignments for families. As well as the seed alignment from which the family is built, we provide the full alignment, generated by searching the sequence database (reference proteomes) using the family HMM. We also generate alignments using four representative proteomes (RP) sets and the UniProtKB sequence database. More...

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We make a range of alignments for each Pfam-A family. You can see a description of each above. You can view these alignments in various ways but please note that some types of alignment are never generated while others may not be available for all families, most commonly because the alignments are too large to handle.

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We make all of our alignments available in Stockholm format. You can download them here as raw, plain text files or as gzip-compressed files.

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You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.

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HMM logos is one way of visualising profile HMMs. Logos provide a quick overview of the properties of an HMM in a graphical form. You can see a more detailed description of HMM logos and find out how you can interpret them here. More...


This page displays the phylogenetic tree for this family's seed alignment. We use FastTree to calculate neighbour join trees with a local bootstrap based on 100 resamples (shown next to the tree nodes). FastTree calculates approximately-maximum-likelihood phylogenetic trees from our seed alignment.

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Curation and family details

This section shows the detailed information about the Pfam family. You can see the definitions of many of the terms in this section in the glossary and a fuller explanation of the scoring system that we use in the scores section of the help pages.

Curation View help on the curation process

Seed source: Overington and HMM_iterative_training
Previous IDs: none
Type: Domain
Sequence Ontology: SO:0000417
Author: Eddy SR
Number in seed: 50
Number in full: 213489
Average length of the domain: 340.7 aa
Average identity of full alignment: 17 %
Average coverage of the sequence by the domain: 78.98 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 61295632 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 22.8 22.8
Trusted cut-off 22.8 22.8
Noise cut-off 22.7 22.7
Model length: 463
Family (HMM) version: 25
Download: download the raw HMM for this family

Species distribution

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Colour assignments

Archea Archea Eukaryota Eukaryota
Bacteria Bacteria Other sequences Other sequences
Viruses Viruses Unclassified Unclassified
Viroids Viroids Unclassified sequence Unclassified sequence


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This visualisation provides a simple graphical representation of the distribution of this family across species. You can find the original interactive tree in the adjacent tab. More...

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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the p450 domain has been found. There are 2175 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein sequence.

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AlphaFold Structure Predictions

The list of proteins below match this family and have AlphaFold predicted structures. Click on the protein accession to view the predicted structure.

Protein Predicted structure External Information
A0A044QY47 View 3D Structure Click here
A0A044QYS1 View 3D Structure Click here
A0A044SLS5 View 3D Structure Click here
A0A044UGM0 View 3D Structure Click here
A0A075TMP8 View 3D Structure Click here
A0A075TRL5 View 3D Structure Click here
A0A077YXG9 View 3D Structure Click here
A0A077Z3T1 View 3D Structure Click here
A0A077ZA68 View 3D Structure Click here
A0A077ZAI9 View 3D Structure Click here
A0A077ZB16 View 3D Structure Click here
A0A077ZC80 View 3D Structure Click here
A0A077ZGA8 View 3D Structure Click here
A0A077ZI65 View 3D Structure Click here
A0A077ZJS9 View 3D Structure Click here
A0A084R1J1 View 3D Structure Click here
A0A084R1J2 View 3D Structure Click here
A0A084R1M6 View 3D Structure Click here
A0A084R1M7 View 3D Structure Click here
A0A087WPC3 View 3D Structure Click here
A0A087WS15 View 3D Structure Click here
A0A087X1C5 View 3D Structure Click here
A0A096PQR7 View 3D Structure Click here
A0A098CZ12 View 3D Structure Click here
A0A098D1J7 View 3D Structure Click here
A0A098DDI4 View 3D Structure Click here
A0A0A2JY25 View 3D Structure Click here
A0A0A2V2N3 View 3D Structure Click here
A0A0A2V731 View 3D Structure Click here
A0A0A2VKB6 View 3D Structure Click here
A0A0A2VLK3 View 3D Structure Click here
A0A0A2VM35 View 3D Structure Click here
A0A0C1E1L9 View 3D Structure Click here
A0A0D1DMJ7 View 3D Structure Click here
A0A0D1DT62 View 3D Structure Click here
A0A0D2D9H3 View 3D Structure Click here
A0A0D2DC50 View 3D Structure Click here
A0A0D2DCD5 View 3D Structure Click here
A0A0D2DEL5 View 3D Structure Click here
A0A0D2DEM7 View 3D Structure Click here