Summary: Interferon alpha/beta domain
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Interferon Edit Wikipedia article
|Interferon alpha/beta domain|
The molecular structure of human interferon-alpha
Interferons (IFNs) are a group of signaling proteins made and released by host cells in response to the presence of several pathogens, such as viruses, bacteria, parasites, and also tumor cells. In a typical scenario, a virus-infected cell will release interferons causing nearby cells to heighten their anti-viral defenses.
IFNs belong to the large class of proteins known as cytokines, molecules used for communication between cells to trigger the protective defenses of the immune system that help eradicate pathogens. Interferons are named for their ability to "interfere" with viral replication by protecting cells from virus infections. IFNs also have various other functions: they activate immune cells, such as natural killer cells and macrophages; they increase host defenses by up-regulating antigen presentation by virtue of increasing the expression of major histocompatibility complex (MHC) antigens. Certain symptoms of infections, such as fever, muscle pain and "flu-like symptoms", are also caused by the production of IFNs and other cytokines.
More than twenty distinct IFN genes and proteins have been identified in animals, including humans. They are typically divided among three classes: Type I IFN, Type II IFN, and Type III IFN. IFNs belonging to all three classes are important for fighting viral infections and for the regulation of the immune system.
Types of interferon
Based on the type of receptor through which they signal, human interferons have been classified into three major types.
- Interferon type I: All type I IFNs bind to a specific cell surface receptor complex known as the IFN-α/β receptor (IFNAR) that consists of IFNAR1 and IFNAR2 chains. The type I interferons present in humans are IFN-α, IFN-β, IFN-ε, IFN-κ and IFN-ω. In general, type I interferons are produced when the body recognizes a virus has invaded it. They are produced by fibroblasts and monocytes. However, the production of type I IFN-α is prohibited by another cytokine known as Interleukin-10. Once released, type I interferons bind to specific receptors on target cells, which leads to expression of proteins that will prevent the virus from producing and replicating its RNA and DNA. Overall, IFN-α can be used to treat hepatitis B and C infections, while IFN-β can be used to treat multiple sclerosis.
- Interferon type II (IFN-γ in humans): This is also known as immune interferon and is activated by Interleukin-12. Furthermore, type II interferons are released by Cytotoxic T cells and T helper cells, type 1 specifically. However, they block the proliferation of T helper cells type two. The previous results in an inhibition of Th2 immune response and a further induction of Th1 immune response, which leads to the development of debilitating diseases such as multiple sclerosis. IFN type II binds to IFNGR, which consists of IFNGR1 and IFNGR2 chains and has a different receptor than type I IFN.
- Interferon type III: Signal through a receptor complex consisting of IL10R2 (also called CRF2-4) and IFNLR1 (also called CRF2-12). Although discovered more recently than type I and type II IFNs, recent information demonstrates the importance of Type III IFNs in some types of virus or fungal infections.
In general, type I and II interferons are responsible for regulating and activating the immune response. Expression of type I and III IFNs can be induced in virtually all cell types upon recognition of viral components, especially nucleic acids, by cytoplasmic and endosomal receptors, whereas type II interferon is induced by cytokines such as IL-12, and its expression is restricted to immune cells such as T cells and NK cells.
All interferons share several common effects: they are antiviral agents and they modulate functions of the immune system. Administration of Type I IFN has been shown experimentally to inhibit tumor growth in animals, but the beneficial action in human tumors has not been widely documented. A virus-infected cell releases viral particles that can infect nearby cells. However, the infected cell can prepare neighboring cells against a potential infection by the virus by releasing interferons. In response to interferon, cells produce large amounts of an enzyme known as protein kinase R (PKR). This enzyme phosphorylates a protein known as eIF-2 in response to new viral infections; the phosphorylated eIF-2 forms an inactive complex with another protein, called eIF2B, to reduce protein synthesis within the cell. Another cellular enzyme, RNAse L—also induced by interferon action—destroys RNA within the cells to further reduce protein synthesis of both viral and host genes. Inhibited protein synthesis destroys both the virus and infected host cells. In addition, interferons induce production of hundreds of other proteins—known collectively as interferon-stimulated genes (ISGs)—that have roles in combating viruses and other actions produced by interferon. They also limit viral spread by increasing p53 activity, which kills virus-infected cells by promoting apoptosis. The effect of IFN on p53 is also linked to its protective role against certain cancers.
Another function of interferons is to upregulate major histocompatibility complex molecules, MHC I and MHC II, and increase immunoproteasome activity. Higher MHC I expression increases presentation of viral peptides to cytotoxic T cells, while the immunoproteasome processes viral peptides for loading onto the MHC I molecule, thereby increasing the recognition and killing of infected cells. Higher MHC II expression increases presentation of viral peptides to helper T cells; these cells release cytokines (such as more interferons and interleukins, among others) that signal to and co-ordinate the activity of other immune cells.
Induction of interferons
Production of interferons occurs mainly in response to microbes, such as viruses and bacteria, and their products. Binding of molecules uniquely found in microbes—viral glycoproteins, viral RNA, bacterial endotoxin (lipopolysaccharide), bacterial flagella, CpG motifs—by pattern recognition receptors, such as membrane bound Toll like receptors or the cytoplasmic receptors RIG-I or MDA5, can trigger release of IFNs. Toll Like Receptor 3 (TLR3) is important for inducing interferons in response to the presence of double-stranded RNA viruses; the ligand for this receptor is double-stranded RNA (dsRNA). After binding dsRNA, this receptor activates the transcription factors IRF3 and NF-κB, which are important for initiating synthesis of many inflammatory proteins. RNA interference technology tools such as siRNA or vector-based reagents can either silence or stimulate interferon pathways. Release of IFN from cells (specifically IFN-γ in lymphoid cells) is also induced by mitogens. Other cytokines, such as interleukin 1, interleukin 2, interleukin-12, tumor necrosis factor and colony-stimulating factor, can also enhance interferon production.
By interacting with their specific receptors, IFNs activate signal transducer and activator of transcription (STAT) complexes; STATs are a family of transcription factors that regulate the expression of certain immune system genes. Some STATs are activated by both type I and type II IFNs. However each IFN type can also activate unique STATs.
STAT activation initiates the most well-defined cell signaling pathway for all IFNs, the classical Janus kinase-STAT (JAK-STAT) signaling pathway. In this pathway, JAKs associate with IFN receptors and, following receptor engagement with IFN, phosphorylate both STAT1 and STAT2. As a result, an IFN-stimulated gene factor 3 (ISGF3) complex forms—this contains STAT1, STAT2 and a third transcription factor called IRF9—and moves into the cell nucleus. Inside the nucleus, the ISGF3 complex binds to specific nucleotide sequences called IFN-stimulated response elements (ISREs) in the promoters of certain genes, known as IFN stimulated genes ISGs. Binding of ISGF3 and other transcriptional complexes activated by IFN signaling to these specific regulatory elements induces transcription of those genes. A collection of known ISGs is available on Interferome, a curated online database of ISGs (www.interferome.org); Additionally, STAT homodimers or heterodimers form from different combinations of STAT-1, -3, -4, -5, or -6 during IFN signaling; these dimers initiate gene transcription by binding to IFN-activated site (GAS) elements in gene promoters. Type I IFNs can induce expression of genes with either ISRE or GAS elements, but gene induction by type II IFN can occur only in the presence of a GAS element.
In addition to the JAK-STAT pathway, IFNs can activate several other signaling cascades. For instance, both type I and type II IFNs activate a member of the CRK family of adaptor proteins called CRKL, a nuclear adaptor for STAT5 that also regulates signaling through the C3G/Rap1 pathway. Type I IFNs further activate p38 mitogen-activated protein kinase (MAP kinase) to induce gene transcription. Antiviral and antiproliferative effects specific to type I IFNs result from p38 MAP kinase signaling. The phosphatidylinositol 3-kinase (PI3K) signaling pathway is also regulated by both type I and type II IFNs. PI3K activates P70-S6 Kinase 1, an enzyme that increases protein synthesis and cell proliferation; phosphorylates of ribosomal protein s6, which is involved in protein synthesis; and phosphorylates a translational repressor protein called eukaryotic translation-initiation factor 4E-binding protein 1 (EIF4EBP1) in order to deactivate it.
Interferons can disrupt signaling by other stimuli. For example, Interferon alpha induces RIG-G, which disrupts the CSN5-containing COP9 signalosome (CSN), a highly conserved multiprotein complex implicated in protein deneddylation, deubiquitination, and phosphorylation. RIG-G has shown the capacity to inhibit NF-κB and STAT3 signaling in lung cancer cells, which demonstrates the potential of type I IFNs.
Virus resistance to interferons
Many viruses have evolved mechanisms to resist interferon activity. They circumvent the IFN response by blocking downstream signaling events that occur after the cytokine binds to its receptor, by preventing further IFN production, and by inhibiting the functions of proteins that are induced by IFN. Viruses that inhibit IFN signaling include Japanese Encephalitis Virus (JEV), dengue type 2 virus (DEN-2) and viruses of the herpesvirus family, such as human cytomegalovirus (HCMV) and Kaposi's sarcoma-associated herpesvirus (KSHV or HHV8). Viral proteins proven to affect IFN signaling include EBV nuclear antigen 1 (EBNA1) and EBV nuclear antigen 2 (EBNA-2) from Epstein-Barr virus, the large T antigen of Polyomavirus, the E7 protein of Human papillomavirus (HPV), and the B18R protein of vaccinia virus. Reducing IFN-α activity may prevent signaling via STAT1, STAT2, or IRF9 (as with JEV infection) or through the JAK-STAT pathway (as with DEN-2 infection). Several poxviruses encode soluble IFN receptor homologs—like the B18R protein of the vaccinia virus—that bind to and prevent IFN interacting with its cellular receptor, impeding communication between this cytokine and its target cells. Some viruses can encode proteins that bind to double-stranded RNA (dsRNA) to prevent the activity of RNA-dependent protein kinases; this is the mechanism reovirus adopts using its sigma 3 (σ3) protein, and vaccinia virus employs using the gene product of its E3L gene, p25. The ability of interferon to induce protein production from interferon stimulated genes (ISGs) can also be affected. Production of protein kinase R, for example, can be disrupted in cells infected with JEV  Some viruses escape the anti-viral activities of interferons by gene (and thus protein) mutation. The H5N1 influenza virus, also known as bird flu, has resistance to interferon and other anti-viral cytokines that is attributed to a single amino acid change in its Non-Structural Protein 1 (NS1), although the precise mechanism of how this confers immunity is unclear.
Interferon beta-1a and interferon beta-1b are used to treat and control multiple sclerosis, an autoimmune disorder. This treatment is effective for reducing attacks in relapsing-remitting multiple sclerosis and slowing disease progression and activity in secondary progressive multiple sclerosis.
Interferon therapy is used (in combination with chemotherapy and radiation) as a treatment for some cancers. This treatment can be used in hematological malignancy; leukemia and lymphomas including hairy cell leukemia, chronic myeloid leukemia, nodular lymphoma, and cutaneous T-cell lymphoma. Patients with recurrent melanomas receive recombinant IFN-α2b. Both hepatitis B and hepatitis C are treated with IFN-α, often in combination with other antiviral drugs. Some of those treated with interferon have a sustained virological response and can eliminate hepatitis virus. The most harmful strain—hepatitis C genotype I virus—can be treated with a 60-80% success rate with the current standard-of-care treatment of interferon-α, ribavirin and recently approved protease inhibitors such as Telaprevir (Incivek) May 2011, Boceprevir (Victrelis) May 2011 or the nucleotide analog polymerase inhibitor Sofosbuvir (Sovaldi) December 2013. Biopsies of patients given the treatment show reductions in liver damage and cirrhosis. Some evidence shows giving interferon immediately following infection can prevent chronic hepatitis C, although diagnosis early in infection is difficult since physical symptoms are sparse in early hepatitis C infection. Control of chronic hepatitis C by IFN is associated with reduced hepatocellular carcinoma.
There is low-quality evidence suggesting that interferon eye drops may be an effective treatment for people who have herpes simplex virus epithelial keratitis, a type of eye infection. There is no clear evidence to suggest that removing the infected tissue (debridement) followed by interferon drops is an effective treatment approach for these types of eye infections. Low-quality evidence suggests that the combination of interferon and an antiviral agent may speed the healing process compared to antiviral therapy alone.
When used in the systemic therapy, IFNs are mostly administered by an intramuscular injection. The injection of IFNs in the muscle or under the skin is generally well tolerated. The most frequent adverse effects are flu-like symptoms: increased body temperature, feeling ill, fatigue, headache, muscle pain, convulsion, dizziness, hair thinning, and depression. Erythema, pain, and hardness on the spot of injection are also frequently observed. IFN therapy causes immunosuppression, in particular through neutropenia and can result in some infections manifesting in unusual ways.
|Generic name||Trade name|
|Interferon alpha 2a||Roferon A|
|Interferon alpha 2b||Intron A/Reliferon/Uniferon|
|Human leukocyte Interferon-alpha (HuIFN-alpha-Le)||Multiferon|
|Interferon beta 1a, liquid form||Rebif|
|Interferon beta 1a, lyophilized||Avonex|
|Interferon beta 1a, biogeneric (Iran)||Cinnovex|
|Interferon beta 1b||Betaseron / Betaferon|
|Interferon gamma 1b||Actimmune|
|PEGylated interferon alpha 2a||Pegasys|
|PEGylated interferon alpha 2a (Egypt)||Reiferon Retard|
|PEGylated interferon alpha 2b||PegIntron|
|PEGylated interferon alpha 2b plus ribavirin (Canada)||Pegetron|
Several different types of interferons are approved for use in humans. One was first approved for medical use in 1986. For example, in January 2001, the Food and Drug Administration (FDA) approved the use of PEGylated interferon-alpha in the USA; in this formulation, PEGylated interferon-alpha-2b (Pegintron), polyethylene glycol is linked to the interferon molecule to make the interferon last longer in the body. Approval for PEGylated interferon-alpha-2a (Pegasys) followed in October 2002. These PEGylated drugs are injected once weekly, rather than administering two or three times per week, as is necessary for conventional interferon-alpha. When used with the antiviral drug ribavirin, PEGylated interferon is effective in treatment of hepatitis C; at least 75% of people with hepatitis C genotypes 2 or 3 benefit from interferon treatment, although this is effective in less than 50% of people infected with genotype 1 (the more common form of hepatitis C virus in both the U.S. and Western Europe). Interferon-containing regimens may also include protease inhibitors such as boceprevir and telaprevir.
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Interferons were first described in 1957 by Alick Isaacs and Jean Lindenmann at the National Institute for Medical Research in London; the discovery was a result of their studies of viral interference. Viral interference refers to the inhibition of virus growth caused by previous exposure of cells to an active or a heat-inactivated virus. Isaacs and Lindenmann were working with a system that involved the inhibition of the growth of live influenza virus in chicken embryo chorioallantoic membranes by heat-inactivated influenza virus. Their experiments revealed that this interference was mediated by a protein released by cells in the heat-inactivated influenza virus-treated membranes. They published their results in 1957 naming the antiviral factor they had discovered interferon. The findings of Isaacs and Lindenmann have been widely confirmed and corroborated in the literature.
Furthermore, others may have made observations on interferons before the 1957 publication of Isaacs and Lindenmann. For example, during research to produce a more efficient vaccine for smallpox, Yasu-ichi Nagano and Yasuhiko Kojima—two Japanese virologists working at the Institute for Infectious Diseases at the University of Tokyo—noticed inhibition of viral growth in an area of rabbit-skin or testis previously inoculated with UV-inactivated virus. They hypothesised that some "viral inhibitory factor" was present in the tissues infected with virus and attempted to isolate and characterize this factor from tissue homogenates. Independently, Monto Ho, in John Enders's lab, observed in 1957 that attenuated poliovirus conferred a species specific anti-viral effect in human amniotic cell cultures. They described these observations in a 1959 publication, naming the responsible factor viral inhibitory factor (VIF). It took another fifteen to twenty years, using somatic cell genetics, to show that the interferon action gene and interferon gene reside in different human chromosomes. The purification of human beta interferon did not occur until 1977. Chris Y.H. Tan and his co-workers purified and produced biologically active, radio-labeled human beta interferon by superinducing the interferon gene in fibroblast cells, and they showed its active site contains tyrosine residues. Tan's laboratory isolated sufficient amounts of human beta interferon to perform the first amino acid, sugar composition and N-terminal analyses. They showed that human beta interferon was an unusually hydrophobic glycoprotein. This explained the large loss of interferon activity when preparations were transferred from test tube to test tube or from vessel to vessel during purification. The analyses showed the reality of interferon activity by chemical verification. The purification of human alpha interferon was not reported until 1978. A series of publications from the laboratories of Sidney Pestka and Alan Waldman between 1978 and 1981, describe the purification of the type I interferons IFN-α and IFN-β. By the early 1980s, genes for these interferons had been cloned, adding further definitive proof that interferons were responsible for interfering with viral replication. Gene cloning also confirmed that IFN-α was encoded by a family of many related genes. The type II IFN (IFN-γ) gene was also isolated around this time.
Interferon was scarce and expensive until 1980, when the interferon gene was inserted into bacteria using recombinant DNA technology, allowing mass cultivation and purification from bacterial cultures or derived from yeasts. Interferon can also be produced by recombinant mammalian cells. Before the early 1970s, large scale production of human interferon had been pioneered by Kari Cantell. He produced large amounts of human alpha interferon from large quantities of human white blood cells collected by the Finnish Blood Bank. Large amounts of human beta interferon were made by superinducing the beta interferon gene in human fibroblast cells.
Cantell's and Tan's methods of making large amounts of natural interferon were critical for chemical characterisation, clinical trials and the preparation of small amounts of interferon messenger RNA to clone the human alpha and beta interferon genes. The superinduced human beta interferon messenger RNA was prepared by Tan's lab for Cetus corp. to clone the human beta interferon gene in bacteria and the recombinant interferon was developed as 'betaseron' and approved for the treatment of MS. Superinduction of the human beta interferon gene was also used by Israeli scientists to manufacture human beta interferon.
- ATC code L03#L03AB Interferons
- Immunosuppressive drug
- Interferon Consensus Sequence-binding protein
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- Sharieff KA, Duncan D, Younossi Z (February 2002). "Advances in treatment of chronic hepatitis C: 'pegylated' interferons". Cleveland Clinic Journal of Medicine. 69 (2): 155–9. doi:10.3949/ccjm.69.2.155. PMID 11990646.
- Kolata, Gina (2015-01-22). "Jean Lindenmann, Who Made Interferon His Life's Work, Is Dead at 90". The New York Times. Retrieved 2015-02-12.
- Isaacs A, Lindenmann J (September 1957). "Virus interference. I. The interferon". Proceedings of the Royal Society of London. Series B, Biological Sciences. 147 (927): 258–67. Bibcode:1957RSPSB.147..258I. doi:10.1098/rspb.1957.0048. PMID 13465720.
- Pestka S (July 2007). "The interferons: 50 years after their discovery, there is much more to learn". The Journal of Biological Chemistry. 282 (28): 20047–51. doi:10.1074/jbc.R700004200. PMID 17502369.
- W.E. Stewart II (2013-04-17). The Interferon System. Springer Science & Business Media. p. 1. ISBN 978-3-7091-3432-0.
- Nagano Y, Kojima Y (October 1954). "[Immunizing property of vaccinia virus inactivated by ultraviolets rays]". Comptes Rendus Des Seances De La Societe De Biologie Et De Ses Filiales (in French). 148 (19-20): 1700–2. PMID 14364998.
- Ho M, Enders JF (March 1959). "AN INHIBITOR OF VIRAL ACTIVITY APPEARING IN INFECTED CELL CULTURES". Proceedings of the National Academy of Sciences of the United States of America. 45 (3): 385–9. PMC . PMID 16590396.
- Tan YH, Tischfield J, Ruddle FH (February 1973). "The linkage of genes for the human interferon-induced antiviral protein and indophenol oxidase-B traits to chromosome G-21". The Journal of Experimental Medicine. 137 (2): 317–30. doi:10.1084/jem.137.2.317. PMC . PMID 4346649.
- Tan YH (March 1976). "Chromosome 21 and the cell growth inhibitory effect of human interferon preparations". Nature. 260 (5547): 141–3. Bibcode:1976Natur.260..141T. doi:10.1038/260141a0. PMID 176593.
- Meager A, Graves H, Burke DC, Swallow DM (August 1979). "Involvement of a gene on chromosome 9 in human fibroblast interferon production". Nature. 280 (5722): 493–5. Bibcode:1979Natur.280..493M. doi:10.1038/280493a0. PMID 460428.
- Berthold W, Tan C, Tan YH (June 1978). "Chemical modifications of tyrosyl residue(s) and action of human-fibroblast interferon". European Journal of Biochemistry. 87 (2): 367–70. doi:10.1111/j.1432-1033.1978.tb12385.x. PMID 678325.
- Berthold W, Tan C, Tan YH (July 1978). "Purification and in vitro labeling of interferon from a human fibroblastoid cell line". The Journal of Biological Chemistry. 253 (14): 5206–12. PMID 670186.
- Tan YH, Barakat F, Berthold W, Smith-Johannsen H, Tan C (August 1979). "The isolation and amino acid/sugar composition of human fibroblastoid interferon". The Journal of Biological Chemistry. 254 (16): 8067–73. PMID 468807.
- Zoon KC, Smith ME, Bridgen PJ, Anfinsen CB, Hunkapiller MW, Hood LE (February 1980). "Amino terminal sequence of the major component of human lymphoblastoid interferon". Science. 207 (4430): 527–8. Bibcode:1980Sci...207..527Z. doi:10.1126/science.7352260. PMID 7352260.
- Okamura H, Berthold W, Hood L, Hunkapiller M, Inoue M, Smith-Johannsen H, Tan YH (August 1980). "Human fibroblastoid interferon: immunosorbent column chromatography and N-terminal amino acid sequence". Biochemistry. 19 (16): 3831–5. doi:10.1021/bi00557a028. PMID 6157401.
- Knight E, Hunkapiller MW, Korant BD, Hardy RW, Hood LE (February 1980). "Human fibroblast interferon: amino acid analysis and amino terminal amino acid sequence". Science. 207 (4430): 525–6. Bibcode:1980Sci...207..525K. doi:10.1126/science.7352259. PMID 7352259.
- Weissenbach J, Chernajovsky Y, Zeevi M, Shulman L, Soreq H, Nir U, Wallach D, Perricaudet M, Tiollais P, Revel M (December 1980). "Two interferon mRNAs in human fibroblasts: in vitro translation and Escherichia coli cloning studies". Proceedings of the National Academy of Sciences of the United States of America. 77 (12): 7152–6. Bibcode:1980PNAS...77.7152W. doi:10.1073/pnas.77.12.7152. PMC . PMID 6164058.
- Taniguchi T, Fujii-Kuriyama Y, Muramatsu M (July 1980). "Molecular cloning of human interferon cDNA". Proceedings of the National Academy of Sciences of the United States of America. 77 (7): 4003–6. Bibcode:1980PNAS...77.4003T. doi:10.1073/pnas.77.7.4003. PMC . PMID 6159625.
- Nagata S, Mantei N, Weissmann C (October 1980). "The structure of one of the eight or more distinct chromosomal genes for human interferon-alpha". Nature. 287 (5781): 401–8. Bibcode:1980Natur.287..401N. doi:10.1038/287401a0. PMID 6159536.
- Gray PW, Goeddel DV (August 1982). "Structure of the human immune interferon gene". Nature. 298 (5877): 859–63. Bibcode:1982Natur.298..859G. doi:10.1038/298859a0. PMID 6180322.
- Nagata S, Taira H, Hall A, Johnsrud L, Streuli M, Ecsödi J, Boll W, Cantell K, Weissmann C (March 1980). "Synthesis in E. coli of a polypeptide with human leukocyte interferon activity". Nature. 284 (5754): 316–20. Bibcode:1980Natur.284..316N. doi:10.1038/284316a0. PMID 6987533.
- US patent 6207146, Tan YH, Hong WJ, "Gene expression in mammalian cells.", issued 2001
- Cantell K (1998). The story of interferon: the ups and downs in the life of a scientis. Singapore ; New York: World Scientific. ISBN 978-981-02-3148-4.
- Tan YH, Armstrong JA, Ke YH, Ho M (September 1970). "Regulation of cellular interferon production: enhancement by antimetabolites". Proceedings of the National Academy of Sciences of the United States of America. 67 (1): 464–71. Bibcode:1970PNAS...67..464T. doi:10.1073/pnas.67.1.464. PMC . PMID 5272327.
- US patent 3773924, Ho M, Armstrong JA, Ke YH, Tan YH, "Interferon Production", issued 1973
- Bekisz J, Schmeisser H, Hernandez J, Goldman ND, Zoon KC (December 2004). "Human interferons alpha, beta and omega". Growth Factors. 22 (4): 243–51. doi:10.1080/08977190400000833. PMID 15621727.
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.
Interferon alpha/beta domain Provide feedback
No Pfam abstract.
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR000471Interferons [PUBMED:3022999] are proteins which produce antiviral and antiproliferative responses in cells. On the basis of their sequence interferons are classified into five groups: alpha, alpha-II (or omega), beta, delta (or trophoblast) and gamma. Proteins in this entry are different from the interferon gamma family. The sequence differences may possibly cause different responses to various inducers, or result in the recognition of different target cell types [PUBMED:6170983]. All function as regulators of cellular activty by interacting with cell-surface receptors and activating various signalling pathways. Interferons produce antiviral and antiproliferative responses in cells. Receptor specificity determines function of the various members of the family [PUBMED:10547147]. The main conserved structural feature of interferons is a disulphide bond that, except in mouse beta interferon, occurs in all alpha, beta and omega sequences.
Type I interferons (alpha, beta) belong to the larger helical cytokine superfamily, which includes growth hormones, interleukins, several colony-stimulating factors and several other regulatory molecules. This entry also includes also interferon omega and tau.
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Cellular component||extracellular region (GO:0005576)|
|Molecular function||cytokine receptor binding (GO:0005126)|
|Biological process||defense response (GO:0006952)|
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.
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Cytokines are regulatory peptides that can be produced by various cells for communicating and orchestrating the large multicellular system. Cytokines are key mediators of hematopoiesis, immunity, allergy, inflammation, tissue remodeling, angiogenesis, and embryonic development . This superfamily includes both the long and short chain helical cytokines.
The clan contains the following 29 members:CNTF CSF-1 EPO_TPO Flt3_lig GCSF GM_CSF Hormone_1 IFN-gamma IL10 IL11 IL12 IL13 IL15 IL2 IL22 IL23 IL28A IL3 IL34 IL4 IL5 IL6 IL7 Interferon Leptin LIF_OSM PRF SCF TSLP
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, the UniProtKB sequence database, 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 UniProtKB sequence database using the family HMM
- 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.
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.
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.
|Number in seed:||118|
|Number in full:||792|
|Average length of the domain:||153.10 aa|
|Average identity of full alignment:||34 %|
|Average coverage of the sequence by the domain:||83.17 %|
|HMM build commands:||
build method: hmmbuild --amino -o /dev/null HMM SEED
search method: hmmsearch -Z 45638612 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||19|
|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 7 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 Interferon domain has been found. There are 37 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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