| Type: | Domain | Name: | Interferon regulatory factor DNA-binding domain |
| Description: | Viral infections induce the expression of type I interferons (IFN-alpha and IFN-beta) genes. The induction is due to the transcriptional activation of theIFN genes. Interferon regulatory factor I (IRF-1) is one of the transcription factors responsible for that activation. IRF-1 binds to an upstream regulatorycis element, known as the interferon consensus sequence (ICS), which is found in 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, but that 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 amino acid residues which is involved in DNA-binding and which contain five conserved 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 transcriptionfactor expressed predominantly in lymphoid tissues and induced by IFN-gamma that also binds to the ICS.Transcriptional regulator ISGF3 gamma subunit []. ISGF3 is responsible forthe initial stimulation of interferon-alpha-responsive genes. It recognises and binds to the interferon-stimulated response element (ISRE) within theregulatory 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 norvIRF-2 bind to DNA with the same specificity as cellular IRFs, indicating that if vIRFs are DNA-binding proteins, their binding has a patterndistinct 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/beta architecture 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 consensus sequences found in target promoters. Three of the tryptophan residues contactDNA by recognising a GAAA sequence [].This entry represents the IRF tryptophan pentad repeat DNA-binding domain. | Short Name: | Interferon_reg_fact_DNA-bd_dom |
