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QuickView for response to interferon- gamma (biogroup)
- Description:
- Viral infections induce the expression of type I interferons (IFN-alpha andIFN-beta) genes. The induction is due to the transcriptional activation of theIFN genes. Interferon regulatory factor I (IRF-1) is one of the transcriptionfactors responsible for that activation. IRF-1 binds to an upstream regulatorycis element, known as the interferon consensus sequence (ICS), which is foundin the promoters of type I IFN and IFN-inducible MHC class I genes. Interferonregulatory factor 2 (IRF-2) is a protein that also interacts with the ICS, butthat does not function as an activator; rather, it suppresses the function ofIRF-1 under certain circumstances.These proteins share a highly conserved N-terminal domain of about 100 aminoacid residues which is involved in DNA-binding and which contain fiveconserved tryptophans. This domain is known as a 'tryptophan pentad repeat' ora 'tryptophan cluster' and is also present in:Interferon consensus sequence binding protein (ICSBP), a transcription factor expressed predominantly in lymphoid tissues and induced by IFN-gamma that also binds to the ICS.Transcriptional regulator ISGF3 gamma subunit. ISGF3 is responsible for the initial stimulation of interferon-alpha-responsive genes. It recognises and binds to the interferon-stimulated response element (ISRE) within the regulatory sequences of target genes.Interferon regulatory factor 3 (IRF-3).Interferon regulatory factor 4 (IRF-4) which binds to the interferon- stimulated response element (ISRE) of the MHC class I promoter.Interferon regulatory factor 5 (IRF-5).Interferon regulatory factor 6 (IRF-6).Interferon regulatory factor 7 (IRF-7).Gamma Herpesviruses vIRF-1, -2 and -3, proteins with homology to the cellular transcription factors of the IRF family. Neither vIRF-1 nor vIRF-2 bind to DNA with the same specificity as cellular IRFs, indicating that if vIRFs are DNA-binding proteins, their binding has a pattern distinct from that of the cellular IRFs. Whether vIRF-3 can bind DNA with the same specificity as cellular IRFs is not known.The IRF tryptophan pentad repeat DNA-binding domain has an alpha/betaarchitecture comprising a cluster of three alpha-helices (alpha1-alpha3)flanked on one side by a mixed four-stranded beta-sheet (beta1-beta4). It forms a helix-turn-helix motif that binds to ISRE consensussequences found in target promoters. Three of the tryptophan residues contactDNA by recognising a GAAA sequence.This entry represents the IRF tryptophan pentad repeat DNA-bindingdomain.
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