Summary: Dihydrofolate reductase
Pfam includes annotations and additional family information from a range of different sources. These sources can be accessed via the tabs below.
This is the Wikipedia entry entitled "Dihydrofolate reductase". More...
The Wikipedia text that you see displayed here is a download from Wikipedia. This means that the information we display is a copy of the information from the Wikipedia database. The button next to the article title ("Edit Wikipedia article") takes you to the edit page for the article directly within Wikipedia. You should be aware you are not editing our local copy of this information. Any changes that you make to the Wikipedia article will not be displayed here until we next download the article from Wikipedia. We currently download new content on a nightly basis.
Does Pfam agree with the content of the Wikipedia entry ?
Pfam has chosen to link families to Wikipedia articles. In some case we have created or edited these articles but in many other cases we have not made any direct contribution to the content of the article. The Wikipedia community does monitor edits to try to ensure that (a) the quality of article annotation increases, and (b) vandalism is very quickly dealt with. However, we would like to emphasise that Pfam does not curate the Wikipedia entries and we cannot guarantee the accuracy of the information on the Wikipedia page.
Editing Wikipedia articles
Before you edit for the first time
Wikipedia is a free, online encyclopedia. Although anyone can edit or contribute to an article, Wikipedia has some strong editing guidelines and policies, which promote the Wikipedia standard of style and etiquette. Your edits and contributions are more likely to be accepted (and remain) if they are in accordance with this policy.
You should take a few minutes to view the following pages:
How your contribution will be recorded
Anyone can edit a Wikipedia entry. You can do this either as a new user or you can register with Wikipedia and log on. When you click on the "Edit Wikipedia article" button, your browser will direct you to the edit page for this entry in Wikipedia. If you are a registered user and currently logged in, your changes will be recorded under your Wikipedia user name. However, if you are not a registered user or are not logged on, your changes will be logged under your computer's IP address. This has two main implications. Firstly, as a registered Wikipedia user your edits are more likely seen as valuable contribution (although all edits are open to community scrutiny regardless). Secondly, if you edit under an IP address you may be sharing this IP address with other users. If your IP address has previously been blocked (due to being flagged as a source of 'vandalism') your edits will also be blocked. You can find more information on this and creating a user account at Wikipedia.
If you have problems editing a particular page, contact us at firstname.lastname@example.org and we will try to help.
The community annotation is a new facility of the Pfam web site. If you have problems editing or experience problems with these pages please contact us.
Dihydrofolate reductase Edit Wikipedia article
||This article may be too technical for most readers to understand. (January 2013)|
Crystal structure of chicken liver dihydrofolate reductase. PDB entry
|PDB structures||RCSB PDB PDBe PDBsum|
|Gene Ontology||AmiGO / EGO|
|R67 dihydrofolate reductase|
High-resolution structure of a plasmid-encoded dihydrofolate reductase from E.coli. PDB entry
Ribbon diagram of human dihydrofolate reductase in complex with folate (blue). From PDB 1DRF.
|External IDs||ChEMBL: GeneCards:|
Dihydrofolate reductase, or DHFR, is an enzyme that reduces dihydrofolic acid to tetrahydrofolic acid, using NADPH as electron donor, which can be converted to the kinds of tetrahydrofolate cofactors used in 1-carbon transfer chemistry. In humans, the DHFR enzyme is encoded by the DHFR gene. It is found in the q11→q22 region of chromosome 5.
Bacterial species possesses distinct DHFR enzymes (based on their pattern of binding diaminoheterocyclic molecules), but mammalian DHFRs are highly similar. The plasmid-encoded DHFR (R67 dihydrofolate reductase) shows a high level of resistance to the antibiotic trimethoprim. It is a homotetramer with an unusual pore, which contains the active site, passing through the middle of the molecule. Its structure is unrelated to that of chromosomal DHFRs.
A central eight-stranded beta-pleated sheet makes up the main feature of the polypeptide backbone folding of DHFR. Seven of these strands are parallel and the eighth runs antiparallel. Four alpha helices connect successive beta strands. Residues 9 – 24 are termed “Met20” or “loop 1” and, along with other loops, are part of the major subdomain that surround the active site. The active site is situated in the N-terminal half of the sequence, which includes a conserved Pro-Trp dipeptide; the tryptophan has been shown to be involved in the binding of substrate by the enzyme.
Dihydrofolate reductase converts dihydrofolate into tetrahydrofolate, a methyl group shuttle required for the de novo synthesis of purines, thymidylic acid, and certain amino acids. While the functional dihydrofolate reductase gene has been mapped to chromosome 5, multiple intronless processed pseudogenes or dihydrofolate reductase-like genes have been identified on separate chromosomes.
DHFR catalyzes the transfer of a hydride from NADPH to dihydrofolate with an accompanying protonation to produce tetrahydrofolate. In the end, dihydrofolate is reduced to tetrahydrofolate and NADPH is oxidized to NADP+. The high flexibility of Met20 and other loops near the active site play a role in promoting the release of the product, tetrahydrofolate. In particular the Met20 loop helps stabilize the nicotinamide ring of the NADPH to promote the transfer of the hydride from NADPH to dihydrofolate.
Found in all organisms, DHFR has a critical role in regulating the amount of tetrahydrofolate in the cell. Tetrahydrofolate and its derivatives are essential for purine and thymidylate synthesis, which are important for cell proliferation and cell growth. DHFR plays a central role in the synthesis of nucleic acid precursors, and it has been shown that mutant cells that completely lack DHFR require glycine, an amino acid, and thymidine to grow. DHFR has also been demonstrated as an enzyme involved in the salvage of tetrahydrobiopterin from dihydrobiopterin 
Dihydrofolate reductase deficiency has been linked to megaloblastic anemia. Treatment is with reduced forms of folic acid. Because tetrahydrofolate, the product of this reaction, is the active form of folate in humans, inhibition of DHFR can cause functional folate deficiency. Its central role in DNA precursor synthesis, coupled with its inhibition by antagonists such as trimethoprim and methotrexate, which are used as anti-bacterial or anti-cancer agents, has made DHFR a target of anticancer chemotherapy. However, resistance has developed against some drugs, as a result of changes in DHFR itself.
Therapeutic application and disease relevance
Since folate is needed by rapidly dividing cells to make thymine, this effect may be used to therapeutic advantage.
DHFR can be targeted in the treatment of cancer. DHFR is responsible for the levels of tetrahydrofolate in a cell, and the inhibition of DHFR can limit the growth and proliferation of cells that are characteristic of cancer. Methotrexate, a competitive inhibitor of DHFR, is one such anticancer drug that inhibits DHFR. Other drugs include trimethoprim and pyrimethamine. These three are widely used as antitumor and antimicrobial agents. Whether or not these are potent anticancer agents is unclear.
Trimethoprim has shown to have activity against a variety of Gram-positive bacterial pathogens. However, resistance to trimethoprim and other drugs aimed at DHFR can arise due to a variety of mechanisms, limiting the success of their therapeutical uses. Resistance can arise from DHFR gene amplification, mutations in DHFR, decrease in the uptake of the drugs, among others. Regardless, trimethoprim and sulfamethoxazole in combination has been used as an antibacterial agent for decades.
Folic acid is necessary for growth, and the pathway of the metabolism of folic acid is a target in developing treatments for cancer. DHFR is one such target. A regimen of fluorouracil, doxorubicin, and methotrexate was shown to prolong survival in patients with advanced gastric cancer. Further studies into inhibitors of DHFR can lead to more ways to treat cancer.
Application as a research tool
Interactive pathway map
Click on genes, proteins and metabolites below to link to respective articles. [§ 1]
- The interactive pathway map can be edited at WikiPathways: "FluoropyrimidineActivity_WP1601".
- Chen MJ, Shimada T, Moulton AD, Harrison M, Nienhuis AW (December 1982). "Intronless human dihydrofolate reductase genes are derived from processed RNA molecules". Proc. Natl. Acad. Sci. U.S.A. 79 (23): 7435–9. doi:10.1073/pnas.79.23.7435. PMC 347354. PMID 6961421.
- Chen MJ, Shimada T, Moulton AD, Cline A, Humphries RK, Maizel J, Nienhuis AW (March 1984). "The functional human dihydrofolate reductase gene". J. Biol. Chem. 259 (6): 3933–43. PMID 6323448.
- Funanage VL, Myoda TT, Moses PA, Cowell HR (October 1984). "Assignment of the human dihydrofolate reductase gene to the q11----q22 region of chromosome 5". Mol. Cell. Biol. 4 (10): 2010–6. PMC 369017. PMID 6504041.
- Smith SL, Patrick P, Stone D, Phillips AW, Burchall JJ (November 1979). "Porcine liver dihydrofolate reductase. Purification, properties, and amino acid sequence". J. Biol. Chem. 254 (22): 11475–84. PMID 500653.
- Narayana N, Matthews DA, Howell EE, Nguyen-huu X (November 1995). "A plasmid-encoded dihydrofolate reductase from trimethoprim-resistant bacteria has a novel D2-symmetric active site". Nat. Struct. Biol. 2 (11): 1018–25. doi:10.1038/nsb1195-1018. PMID 7583655.
- Matthews DA, Alden RA, Bolin JT, Freer ST, Hamlin R, Xuong N, Kraut J, Poe M, Williams M, Hoogsteen K (July 1977). "Dihydrofolate reductase: x-ray structure of the binary complex with methotrexate". Science 197 (4302): 452–455. doi:10.1126/science.17920. PMID 17920.
- Filman DJ, Bolin JT, Matthews DA, Kraut J. (November 1982). "Crystal structure of Escherichia coli and Lactobacillus casei dihydrofolate reductase refined at 1.7 A resolution. II. Environment of bound NADPH and implications for catalysis". The Journal of Biological Chemistry 257 (22): 13650–13662. PMID 6815179.
- Osborne MJ, Schnell J, Benkovic SJ, Dyson HJ, Wright PE (August 2001). "Backbone dynamics in dihydrofolate reductase complexes: role of loop flexibility in the catalytic mechanism". Biochemistry 40 (33): 9846–59. doi:10.1021/bi010621k. PMID 11502178.
- Bolin JT, Filman DJ, Matthews DA, Hamlin RC, Kraut J (November 1982). "Crystal structures of Escherichia coli and Lactobacillus casei dihydrofolate reductase refined at 1.7 A resolution. I. General features and binding of methotrexate". J. Biol. Chem. 257 (22): 13650–62. PMID 6815178.
- "Entrez Gene: DHFR dihydrofolate reductase".
- Schnell JR, Dyson HJ, Wright PE (June 2004). "Structure, dynamics, and catalytic function of dihydrofolate reductase.". Annual Review of Biophysics and Biomolecular Structure 33 (1): 119–40. doi:10.1146/annurev.biophys.33.110502.133613. PMID 15139807.
- Urlaub G, Chasin LA (July 1980). "Isolation of Chinese hamster cell mutants deficient in dihydrofolate reductase activity". Proc. Natl. Acad. Sci. U.S.A. 77 (7): 4216–20. doi:10.1073/pnas.77.7.4216. PMC 349802. PMID 6933469.
- Cowman AF, Lew AM (November 1989). "Antifolate drug selection results in duplication and rearrangement of chromosome 7 in Plasmodium chabaudi". Mol. Cell. Biol. 9 (11): 5182–8. PMC 363670. PMID 2601715.
- Li R, Sirawaraporn R, Chitnumsub P, et al. (January 2000). "Three-dimensional structure of M. tuberculosis dihydrofolate reductase reveals opportunities for the design of novel tuberculosis drugs". J. Mol. Biol. 295 (2): 307–23. doi:10.1006/jmbi.1999.3328. PMID 10623528.
- Benkovic SJ, Fierke CA, Naylor AM (March 1988). "Insights into enzyme function from studies on mutants of dihydrofolate reductase". Science 239 (4844): 1105–10. doi:10.1126/science.3125607. PMID 3125607.
- Hawser S, Lociuro S, Islam K (March 2006). "Dihydrofolate reductase inhibitors as antibacterial agents". Biochem. Pharmacol. 71 (7): 941–8. doi:10.1016/j.bcp.2005.10.052. PMID 16359642.
- Huennekens FM (June 1996). "In search of dihydrofolate reductase". Protein Sci. 5 (6): 1201–8. doi:10.1002/pro.5560050626. PMC 2143423. PMID 8762155.
- Banerjee D, Mayer-Kuckuk P, Capiaux G, Budak-Alpdogan T, Gorlick R, Bertino JR (July 2002). "Novel aspects of resistance to drugs targeted to dihydrofolate reductase and thymidylate synthase". Biochim. Biophys. Acta 1587 (2–3): 164–73. doi:10.1016/S0925-4439(02)00079-0. PMID 12084458.
- Murad AM, Santiago FF, Petroianu A, Rocha PR, Rodrigues MA, Rausch M (July 1993). "Modified therapy with 5-fluorouracil, doxorubicin, and methotrexate in advanced gastric cancer". Cancer 72 (1): 37–41. doi:10.1002/1097-0142(19930701)72:1<37::AID-CNCR2820720109>3.0.CO;2-P. PMID 8508427.
- Mayhew M, da Silva AC, Martin J, Erdjument-Bromage H, Tempst P, Hartl FU (February 1996). "Protein folding in the central cavity of the GroEL-GroES chaperonin complex". Nature 379 (6564): 420–6. doi:10.1038/379420a0. PMID 8559246.
- Maguire M, Nield PC, Devling T, Jenkins RE, Park BK, Polański R, Vlatković N, Boyd MT (May 2008). "MDM2 regulates dihydrofolate reductase activity through monoubiquitination". Cancer Res. 68 (9): 3232–42. doi:10.1158/0008-5472.CAN-07-5271. PMID 18451149.
- Joska TM, Anderson AC (October 2006). "Structure-activity relationships of Bacillus cereus and Bacillus anthracis dihydrofolate reductase: toward the identification of new potent drug leads". Antimicrob. Agents Chemother. 50 (10): 3435–43. doi:10.1128/AAC.00386-06. PMC 1610094. PMID 17005826.
- Chan DC, Fu H, Forsch RA, Queener SF, Rosowsky A (June 2005). "Design, synthesis, and antifolate activity of new analogues of piritrexim and other diaminopyrimidine dihydrofolate reductase inhibitors with omega-carboxyalkoxy or omega-carboxy-1-alkynyl substitution in the side chain". J. Med. Chem. 48 (13): 4420–31. doi:10.1021/jm0581718. PMID 15974594.
- Banerjee D, Mayer-Kuckuk P, Capiaux G, et al. (2002). "Novel aspects of resistance to drugs targeted to dihydrofolate reductase and thymidylate synthase". Biochim. Biophys. Acta 1587 (2–3): 164–73. doi:10.1016/S0925-4439(02)00079-0. PMID 12084458.
- Stockman BJ, Nirmala NR, Wagner G, et al. (1992). "Sequence-specific 1H and 15N resonance assignments for human dihydrofolate reductase in solution". Biochemistry 31 (1): 218–29. doi:10.1021/bi00116a031. PMID 1731871.
- Beltzer JP, Spiess M (1991). "In vitro binding of the asialoglycoprotein receptor to the beta adaptin of plasma membrane coated vesicles". EMBO J. 10 (12): 3735–42. PMC 453108. PMID 1935897.
- Davies JF, Delcamp TJ, Prendergast NJ, et al. (1991). "Crystal structures of recombinant human dihydrofolate reductase complexed with folate and 5-deazafolate". Biochemistry 29 (40): 9467–79. doi:10.1021/bi00492a021. PMID 2248959.
- Will CL, Dolnick BJ (1990). "5-Fluorouracil inhibits dihydrofolate reductase precursor mRNA processing and/or nuclear mRNA stability in methotrexate-resistant KB cells". J. Biol. Chem. 264 (35): 21413–21. PMID 2592384.
- Masters JN, Attardi G (1985). "Discrete human dihydrofolate reductase gene transcripts present in polysomal RNA map with their 5' ends several hundred nucleotides upstream of the main mRNA start site". Mol. Cell. Biol. 5 (3): 493–500. PMC 366741. PMID 2859520.
- Miszta H, Dabrowski Z, Lanotte M (1988). "In vitro patterns of enzymic tetrahydrofolate dehydrogenase (EC 220.127.116.11) expression in bone marrow stromal cells". Leukemia 2 (11): 754–9. PMID 3185016.
- Oefner C, D'Arcy A, Winkler FK (1988). "Crystal structure of human dihydrofolate reductase complexed with folate". Eur. J. Biochem. 174 (2): 377–85. doi:10.1111/j.1432-1033.1988.tb14108.x. PMID 3383852.
- Yang JK, Masters JN, Attardi G (1984). "Human dihydrofolate reductase gene organization. Extensive conservation of the G + C-rich 5' non-coding sequence and strong intron size divergence from homologous mammalian genes". J. Mol. Biol. 176 (2): 169–87. doi:10.1016/0022-2836(84)90419-4. PMID 6235374.
- Masters JN, Yang JK, Cellini A, Attardi G (1983). "A human dihydrofolate reductase pseudogene and its relationship to the multiple forms of specific messenger RNA". J. Mol. Biol. 167 (1): 23–36. doi:10.1016/S0022-2836(83)80032-1. PMID 6306253.
- Chen MJ, Shimada T, Moulton AD, et al. (1984). "The functional human dihydrofolate reductase gene". J. Biol. Chem. 259 (6): 3933–43. PMID 6323448.
- Funanage VL, Myoda TT, Moses PA, Cowell HR (1985). "Assignment of the human dihydrofolate reductase gene to the q11----q22 region of chromosome 5". Mol. Cell. Biol. 4 (10): 2010–6. PMC 369017. PMID 6504041.
- Masters JN, Attardi G (1983). "The nucleotide sequence of the cDNA coding for the human dihydrofolic acid reductase". Gene 21 (1–2): 59–63. doi:10.1016/0378-1119(83)90147-6. PMID 6687716.
- Morandi C, Masters JN, Mottes M, Attardi G (1982). "Multiple forms of human dihydrofolate reductase messenger RNA. Cloning and expression in Escherichia coli of their DNA coding sequence". J. Mol. Biol. 156 (3): 583–607. doi:10.1016/0022-2836(82)90268-6. PMID 6750132.
- Bonifaci N, Sitia R, Rubartelli A (1996). "Nuclear translocation of an exogenous fusion protein containing HIV Tat requires unfolding". AIDS 9 (9): 995–1000. doi:10.1097/00002030-199509000-00003. PMID 8527095.
- Mayhew M, da Silva AC, Martin J, et al. (1996). "Protein folding in the central cavity of the GroEL-GroES chaperonin complex". Nature 379 (6564): 420–6. doi:10.1038/379420a0. PMID 8559246.
- Gross M, Robinson CV, Mayhew M, et al. (1997). "Significant hydrogen exchange protection in GroEL-bound DHFR is maintained during iterative rounds of substrate cycling". Protein Sci. 5 (12): 2506–13. doi:10.1002/pro.5560051213. PMC 2143321. PMID 8976559.
- Schleiff E, Shore GC, Goping IS (1997). "Human mitochondrial import receptor, Tom20p. Use of glutathione to reveal specific interactions between Tom20-glutathione S-transferase and mitochondrial precursor proteins". FEBS Lett. 404 (2–3): 314–8. doi:10.1016/S0014-5793(97)00145-2. PMID 9119086.
- Cody V, Galitsky N, Luft JR, et al. (1997). "Comparison of two independent crystal structures of human dihydrofolate reductase ternary complexes reduced with nicotinamide adenine dinucleotide phosphate and the very tight-binding inhibitor PT523". Biochemistry 36 (45): 13897–903. doi:10.1021/bi971711l. PMID 9374868.
- Vanguri VK, Wang S, Godyna S, et al. (2001). "Thrombospondin-1 binds to polyhistidine with high affinity and specificity". Biochem. J. 347 (Pt 2): 469–73. doi:10.1042/0264-6021:3470469. PMC 1220979. PMID 10749676.
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.
Dihydrofolate reductase Provide feedback
No Pfam abstract.
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR001796
Dihydrofolate reductase (DHFR) (EC) catalyses the NADPH-dependent reduction of dihydrofolate to tetrahydrofolate, an essential step in de novo synthesis both of glycine and of purines and deoxythymidine phosphate (the precursors of DNA synthesis) [PUBMED:2830673], and important also in the conversion of deoxyuridine monophosphate to deoxythymidine monophosphate. Although DHFR is found ubiquitously in prokaryotes and eukaryotes, and is found in all dividing cells, maintaining levels of fully reduced folate coenzymes, the catabolic steps are still not well understood [PUBMED:3383852].
Bacterial species possesses distinct DHFR enzymes (based on their pattern of binding diaminoheterocyclic molecules), but mammalian DHFRs are highly similar [PUBMED:500653]. The active site is situated in the N-terminal half of the sequence, which includes a conserved Pro-Trp dipeptide; the tryptophan has been shown [PUBMED:6815178] to be involved in the binding of substrate by the enzyme. Its central role in DNA precursor synthesis, coupled with its inhibition by antagonists such as trimethoprim and methotrexate, which are used as anti-bacterial or anti-cancer agents, has made DHFR a target of anticancer chemotherapy. However, resistance has developed against some drugs, as a result of changes in DHFR itself [PUBMED:2601715].
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Molecular function||dihydrofolate reductase activity (GO:0004146)|
|Biological process||nucleotide biosynthetic process (GO:0009165)|
|oxidation-reduction process (GO:0055114)|
|glycine biosynthetic process (GO:0006545)|
Below is a listing of the unique domain organisations or architectures in which this domain is found. More...
The graphic that is shown by default represents the longest sequence with a given architecture. Each row contains the following information:
- the number of sequences which exhibit this architecture
a textual description of the architecture, e.g. Gla, EGF x 2, Trypsin.
This example describes an architecture with one
Gladomain, followed by two consecutive
EGFdomains, and finally a single
- a link to the page in the Pfam site showing information about the sequence that the graphic describes
- the UniProt description of the protein sequence
- the number of residues in the sequence
- the Pfam graphic itself.
Note that you can see the family page for a particular domain by clicking on the graphic. You can also choose to see all sequences which have a given architecture by clicking on the Show link in each row.
Finally, because some families can be found in a very large number of architectures, we load only the first fifty architectures by default. If you want to see more architectures, click the button at the bottom of the page to load the next set.
Loading domain graphics...
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 using the family HMM. We also generate alignments using four representative proteomes (RP) sets, the NCBI sequence database, and our metagenomics sequence database. More...
There are various ways to view or download the sequence alignments that we store. We provide several sequence viewers and a plain-text Stockholm-format file for download.
We make a range of alignments for each Pfam-A family:
- the curated alignment from which the HMM for the family is built
- the alignment generated by searching the sequence database using the HMM
- Representative Proteomes (RPs) at 15%, 35%, 55% and 75% co-membership thresholds
- alignment generated by searching the NCBI sequence database using the family HMM
- alignment generated by searching the metagenomics sequence database using the family HMM
You can see the alignments as HTML or in three different sequence viewers:
- a Java applet developed at the University of Dundee. You will need Java installed before running jalview
- an HTML page showing the whole alignment.Please note: full Pfam alignments can be very large. These HTML views are extremely large and often cause problems for browsers. Please use either jalview or the Pfam viewer if you have trouble viewing the HTML version
- an HTML-based representation of the alignment, coloured according to the posterior-probability (PP) values from the HMM. As for the standard HTML view, heatmap alignments can also be very large and slow to render.
- Pfam viewer
- an HTML-based viewer that uses DAS to retrieve alignment fragments on request
You can download (or view in your browser) a text representation of a Pfam alignment in various formats:
You can also change the order in which sequences are listed in the alignment, change how insertions are represented, alter the characters that are used to represent gaps in sequences and, finally, choose whether to download the alignment or to view it in your browser directly.
You may find that large alignments cause problems for the viewers and the reformatting tool, so we also provide all alignments in Stockholm format. You can download either the plain text alignment, or a gzipped version of it.
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.
1Cannot generate PP/Heatmap alignments for seeds; no PP data available
Key: available, not generated, — not available.
Format an alignment
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.
You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.
MyHits provides a collection of tools to handle multiple sequence alignments. For example, one can refine a seed alignment (sequence addition or removal, re-alignment or manual edition) and then search databases for remote homologs using HMMER3.
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...
If you find these logos useful in your own work, please consider citing the following article:
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.
Note: You can also download the data file for the tree.
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.
|Author:||Finn RD, Griffiths-Jones SR|
|Number in seed:||89|
|Number in full:||5237|
|Average length of the domain:||156.60 aa|
|Average identity of full alignment:||33 %|
|Average coverage of the sequence by the domain:||84.23 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||14|
|Download:||download the raw HMM for this family|
Weight segments by...
Change the size of the sunburst
selected sequences to HMM
a FASTA-format file
- 0 sequences
- 0 species
This visualisation provides a simple graphical representation of the distribution of this family across species. You can find the original interactive tree in the More....
This chart is a modified "sunburst" visualisation of the species tree for this family. It shows each node in the tree as a separate arc, arranged radially with the superkingdoms at the centre and the species arrayed around the outermost ring.
How the sunburst is generated
The tree is built by considering the taxonomic lineage of each sequence that has a match to this family. For each node in the resulting tree, we draw an arc in the sunburst. The radius of the arc, its distance from the root node at the centre of the sunburst, shows the taxonomic level ("superkingdom", "kingdom", etc). The length of the arc represents either the number of sequences represented at a given level, or the number of species that are found beneath the node in the tree. The weighting scheme can be changed using the sunburst controls.
In order to reduce the complexity of the representation, we reduce the number of taxonomic levels that we show. We consider only the following eight major taxonomic levels:
Colouring and labels
Segments of the tree are coloured approximately according to their superkingdom. For example, archeal branches are coloured with shades of orange, eukaryotes in shades of purple, etc. The colour assignments are shown under the sunburst controls. Where space allows, the name of the taxonomic level will be written on the arc itself.
As you move your mouse across the sunburst, the current node will be highlighted. In the top section of the controls panel we show a summary of the lineage of the currently highlighed node. If you pause over an arc, a tooltip will be shown, giving the name of the taxonomic level in the title and a summary of the number of sequences and species below that node in the tree.
Anomalies in the taxonomy tree
There are some situations that the sunburst tree cannot easily handle and for which we have work-arounds in place.
Missing taxonomic levels
Some species in the taxonomic tree may not have one or more of the main eight levels that we display. For example, Bos taurus is not assigned an order in the NCBI taxonomic tree. In such cases we mark the omitted level with, for example, "No order", in both the tooltip and the lineage summary.
Unmapped species names
The tree is built by looking at each sequence in the full alignment for the family. We take the name of the species given by UniProt and try to map that to the full taxonomic tree from NCBI. In some cases, the name chosen by UniProt does not map to any node in the NCBI tree, perhaps because the chosen name is listed as a synonym or a misspelling in the NCBI taxonomy.
So that these nodes are not simply omitted from the sunburst tree, we group them together in a separate branch (or segment of the sunburst tree). Since we cannot determine the lineage for these unmapped species, we show all levels between the superkingdom and the species as "uncategorised".
Since we reduce the species tree to only the eight main taxonomic levels, sequences that are mapped to the sub-species level in the tree would not normally be shown. Rather than leave out these species, we map them instead to their parent species. So, for example, for sequences belonging to one of the Vibrio cholerae sub-species in the NCBI taxonomy, we show them instead as belonging to the species Vibrio cholerae.
Too many species/sequences
For large species trees, you may see blank regions in the outer layers of the sunburst. These occur when there are large numbers of arcs to be drawn in a small space. If an arc is less than approximately one pixel wide, it will not be drawn and the space will be left blank. You may still be able to get some information about the species in that region by moving your mouse across the area, but since each arc will be very small, it will be difficult to accurately locate a particular species.
The tree shows the occurrence of this domain across different species. More...
We show the species tree in one of two ways. For smaller trees we try to show an interactive representation, which allows you to select specific nodes in the tree and view them as an alignment or as a set of Pfam domain graphics.
Unfortunately we have found that there are problems viewing the interactive tree when the it becomes larger than a certain limit. Furthermore, we have found that Internet Explorer can become unresponsive when viewing some trees, regardless of their size. We therefore show a text representation of the species tree when the size is above a certain limit or if you are using Internet Explorer to view the site.
If you are using IE you can still load the interactive tree by clicking the "Generate interactive tree" button, but please be aware of the potential problems that the interactive species tree can cause.
For all of the domain matches in a full alignment, we count the number that are found on all sequences in the alignment. This total is shown in the purple box.
We also count the number of unique sequences on which each domain is found, which is shown in green. Note that a domain may appear multiple times on the same sequence, leading to the difference between these two numbers.
Finally, we group sequences from the same organism according to the NCBI code that is assigned by UniProt, allowing us to count the number of distinct sequences on which the domain is found. This value is shown in the pink boxes.
We use the NCBI species tree to group organisms according to their taxonomy and this forms the structure of the displayed tree. Note that in some cases the trees are too large (have too many nodes) to allow us to build an interactive tree, but in most cases you can still view the tree in a plain text, non-interactive representation. Those species which are represented in the seed alignment for this domain are highlighted.
You can use the tree controls to manipulate how the interactive tree is displayed:
- show/hide the summary boxes
- highlight species that are represented in the seed alignment
- expand/collapse the tree or expand it to a given depth
- select a sub-tree or a set of species within the tree and view them graphically or as an alignment
- save a plain text representation of the tree
Please note: for large trees this can take some time. While the tree is loading, you can safely switch away from this tab but if you browse away from the family page entirely, the tree will not be loaded.
There are 2 interactions for this family. More...
We determine these interactions using iPfam, which considers the interactions between residues in three-dimensional protein structures and maps those interactions back to Pfam families. You can find more information about the iPfam algorithm in the journal article that accompanies the website.
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 DHFR_1 domain has been found. There are 438 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 seqence.
Loading structure mapping...