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FUNCTION Innate immune receptor that senses cytoplasmic viral nucleic acids and activates a downstream signaling cascade leading to the production of type I interferons and pro-inflammatory cytokines (PubMed:15208624, PubMed:15708988, PubMed:16125763, PubMed:16127453, PubMed:16153868, PubMed:17190814, PubMed:18636086, PubMed:19122199, PubMed:19211564, PubMed:24366338, PubMed:28469175, PubMed:29117565, PubMed:31006531, PubMed:34935440, PubMed:35263596, PubMed:36793726). Forms a ribonucleoprotein complex with viral RNAs on which it homooligomerizes to form filaments (PubMed:15208624, PubMed:15708988). The homooligomerization allows the recruitment of RNF135 an E3 ubiquitin-protein ligase that activates and amplifies the RIG-I-mediated antiviral signaling in an RNA length-dependent manner through ubiquitination-dependent and -independent mechanisms (PubMed:28469175, PubMed:31006531). Upon activation, associates with mitochondria antiviral signaling protein (MAVS/IPS1) that activates the IKK-related kinases TBK1 and IKBKE which in turn phosphorylate the interferon regulatory factors IRF3 and IRF7, activating transcription of antiviral immunological genes including the IFN-alpha and IFN-beta interferons (PubMed:28469175, PubMed:31006531). Ligands include 5'-triphosphorylated ssRNAs and dsRNAs but also short dsRNAs (<1 kb in length) (PubMed:15208624, PubMed:15708988, PubMed:19576794, PubMed:19609254, PubMed:21742966). In addition to the 5'-triphosphate moiety, blunt-end base pairing at the 5'-end of the RNA is very essential (PubMed:15208624, PubMed:15708988, PubMed:19576794, PubMed:19609254, PubMed:21742966). Overhangs at the non-triphosphorylated end of the dsRNA RNA have no major impact on its activity (PubMed:15208624, PubMed:15708988, PubMed:19576794, PubMed:19609254, PubMed:21742966). A 3'overhang at the 5'triphosphate end decreases and any 5'overhang at the 5' triphosphate end abolishes its activity (PubMed:15208624, PubMed:15708988, PubMed:19576794, PubMed:19609254, PubMed:21742966). Detects both positive and negative strand RNA viruses including members of the families Paramyxoviridae: Human respiratory syncytial virus and measles virus (MeV), Rhabdoviridae: vesicular stomatitis virus (VSV), Orthomyxoviridae: influenza A and B virus, Flaviviridae: Japanese encephalitis virus (JEV), hepatitis C virus (HCV), dengue virus (DENV) and west Nile virus (WNV) (PubMed:21616437, PubMed:21884169). It also detects rotaviruses and reoviruses (PubMed:21616437, PubMed:21884169). Detects and binds to SARS-CoV-2 RNAs which is inhibited by m6A RNA modifications (Ref.74). Also involved in antiviral signaling in response to viruses containing a dsDNA genome such as Epstein-Barr virus (EBV) (PubMed:19631370). Detects dsRNA produced from non-self dsDNA by RNA polymerase III, such as Epstein-Barr virus-encoded RNAs (EBERs). May play important roles in granulocyte production and differentiation, bacterial phagocytosis and in the regulation of cell migration.CATALYTIC ACTIVITY ATP + H2O = ADP + phosphate + H(+)SUBUNIT Monomer; maintained as a monomer in an autoinhibited state. Upon binding of viral RNAs and conformational shift, homooligomerizes and forms filaments on these molecules (PubMed:26471729, PubMed:31881323). Interacts (via tandem CARD domain) with MAVS/IPS1 promoting its filamentation. Interacts with DHX58/LGP2, IKBKE, TBK1 and STING1. Interacts (via CARD domain) with TRIM25 (via SPRY domain). Interacts (double-stranded RNA-bound oligomeric form) with RNF135 (homodimer); involved in RNA length-dependent activation of the RIG-I signaling pathway (PubMed:19017631, PubMed:19484123, PubMed:23950712, PubMed:28469175, PubMed:31006531). Interacts with CYLD. Interacts with NLRC5; blocks the interaction of MAVS/IPS1 to RIGI. Interacts with SRC. Interacts with DDX60. Interacts with isoform 2 of ZC3HAV1 (via zinc-fingers) in an RNA-dependent manner. Interacts (via tandem CARD domain) with SEC14L1; the interaction is direct and impairs the interaction of RIGI with MAVS/IPS1. Interacts with VCP/p97; interaction is direct and allows the recruitment of RNF125 and subsequent ubiquitination and degradation (PubMed:26471729). Interacts with NOP53; may regulate RIGI through USP15-mediated 'Lys-63'-linked deubiquitination (PubMed:27824081). Interacts with SIGLEC10, CBL and PTPN11; within a negative feedback loop leading to RIGI degradation (By similarity). Interacts with LRRC25 (PubMed:29288164). Interacts with ZCCHC3; leading to activation of RIGI (PubMed:30193849). Interacts with RNF123 (PubMed:27312109). Interacts with UBE2D3 and UBE2N; E2 ubiquitin ligases involved in RNF135-mediated ubiquitination of RIGI and activation of the RIG-I signaling pathway (PubMed:28469175). Interacts with IFIT3 (PubMed:21813773). Interacts with DDX3X (PubMed:20127681). Interacts with RTN3 (PubMed:34313226). Interacts with ARL16; this interaction is GTP-dependent and induced upon viral infection; this interaction suppresses the RNA sensing activity of RIGI (PubMed:21233210). Interacts with DHX16; this interaction enhances RIGI-mediated antiviral response (PubMed:35263596). Interacts with IRGM; promoting RIGI degradation (PubMed:32715615). Interacts with IFI6; this interaction inhibits RIGI activation (PubMed:36793726). Interacts with ECSIT; this interaction bridges RIGI to the MAVS complex at the mitochondrion (PubMed:25228397). Interacts with YWHAE; this interaction drives RIGI at the mitochondrion (PubMed:22607805).SUBUNIT (Microbial infection) Interacts with protein Z of Guanarito virus, Machupo virus, Junin arenavirus and Sabia virus. This interaction disrupts its interaction with MAVS/IPS1, impeding downstream IRF3 and NF-kappa-B activation and resulting in decreased IFN-beta induction (PubMed:20007272).SUBUNIT (Microbial infection) Interacts (via CARD domain) with Human respiratory syncytial virus A non-structural protein 2 (NS2) and this interaction disrupts its interaction with MAVS/IPS1, impeding downstream IRF3 activation (PubMed:19193793).SUBUNIT (Microbial infection) Interacts with Rotavirus A non-structural protein 1 (NSP1) and this interaction induces down-regulation of RIGI (PubMed:22152002).SUBUNIT (Microbial infection) Interacts with paramyxoviruses (Sendai virus, Nipah virus, Measles virus and Parainfluenza virus 5) protein V; this interaction inhibits TRIM25-mediated ubiquitination of RIG-I and prevents downstream RIG-I signaling thereby inhibiting the IFN responses.SUBUNIT (Microbial infection) Interacts with herpes simplex virus 1 protein US11; this interaction prevents the interaction of MAVS/IPS1 to RIGI (PubMed:22301138).SUBUNIT (Microbial infection) Interacts with herpes simplex virus 1 protein UL37; this interaction deaminates RIGI and inhibits its activation.SUBUNIT (Microbial infection) Interacts with Severe fever with thrombocytopenia virus (SFTSV) NSs; this interaction this interaction sequesters RIGI in NSs-induced cytoplasmic inclusion bodies thereby inhibiting the IFN responses.INTERACTION Colocalized with TRIM25 at cytoplasmic perinuclear bodies. Associated with the actin cytoskeleton at membrane ruffles.ALTERNATIVE PRODUCTS Present in vascular smooth cells (at protein level).INDUCTION By bacterial lipopolysaccharides (LPS) in endothelial cells. By interferon (IFN).DOMAIN The RLR CTR domain controls homooligomerization and interaction with MAVS/IPS1. In the absence of viral infection, the protein is maintained as a monomer in an autoinhibited state with the CARD domains masked through intramolecular interactions with the RLR CTR domain. Upon binding to viral RNA and ubiquitination by RNF135, a conformational change releases the autoinhibition promoting further homooligomerization, interaction of the CARD domains with the adapter protein MAVS/IPS1 and activation of the downstream RIG-I signaling pathway.DOMAIN The helicase domain is responsible for dsRNA recognition.DOMAIN The 2 CARD domains are responsible for interaction with and signaling through MAVS/IPS1 and for association with the actin cytoskeleton.DOMAIN The second CARD domain is the primary site for 'Lys-63'-linked ubiquitination.PTM Phosphorylated in resting cells and dephosphorylated in RNA virus-infected cells. Phosphorylation at Thr-770, Ser-854 and Ser-855 results in inhibition of its activity while dephosphorylation at these sites results in its activation.PTM Ubiquitinated. 'Lys-63' ubiquitination by RNF135, which occurs after RNA-binding and homodimerization, releases the autoinhibition of the CARD domains by the RLR CTR domain, an essential step in the activation of the RIG-I signaling pathway (PubMed:23950712, PubMed:28469175, PubMed:31006531). Lys-172 is the critical site of ubiquitination for MAVS/IPS1 binding and to induce anti-viral signal transduction (PubMed:17392790, PubMed:30193849). Lys-154, Lys-164 and Lys-172 are shared sites for RNF135-mediated and TRIM4-mediated ubiquitination (PubMed:19017631, PubMed:19484123, PubMed:24755855). Also undergoes 'Lys-48' ubiquitination at Lys-181 by RNF125 that leads to proteasomal degradation (PubMed:17460044, PubMed:26471729). 'Lys-48' ubiquitination follows viral infection and is enhanced by 'Lys-63'-linked ubiquitination of the CARD domains that promotes interaction with VCP/p97 and subsequent recruitment of RNF125 (PubMed:17460044, PubMed:26471729). Within a negative feedback loop involving SIGLEC10 and PTPN11, 'Lys-48' ubiquitination at Lys-812 by CBL also elicits the proteasomal degradation of RIGI (By similarity). Deubiquitinated by CYLD, a protease that selectively cleaves 'Lys-63'-linked ubiquitin chains (PubMed:18636086). Also probably deubiquitinated by USP17L2/USP17 that cleaves 'Lys-48'- and 'Lys-63'-linked ubiquitin chains and positively regulates the receptor (PubMed:20368735). Ubiquitinated by TRIM40 via 'Lys-48'-linked ubiquitination; leading to proteasomal degradation (PubMed:29117565). Deubiquitinated by USP27X that cleaves 'Lys-63'-linked ubiquitin chains and inhibits the innate immune receptor activity (PubMed:32027733). Deubiquitinated by USP3 that also cleaves 'Lys-63'-linked ubiquitin chains and inhibits the innate immune receptor activity (PubMed:24366338). Undergoes 'Lys-48'-linked ubiquitination catalyzed by MARCHF5 at Lys-193 and Lys-203, leading to proteasomal degradation (PubMed:31881323).PTM Phosphorylated at Ser-8 and Thr-170; these phosphorylations suppresse the TRIM25-mediated 'Lys-63'-linked ubiquitination of RIG-I and thereby prevents RIG-I downstream signaling. Dephosphorylated by phosphatases PPP1CA/PPP1CC; this step is essential to activate RIGI and initiate downstream signaling.PTM ISGylated. Conjugated to ubiquitin-like protein ISG15 upon IFN-beta stimulation. ISGylation negatively regulates its function in antiviral signaling response.PTM Sumoylated, probably by MUL1; inhibiting its polyubiquitination.PTM Acetylated in response to RNA virus infection (PubMed:26746851). Deacetylated by HDAC6 in the presence of viral mRNAs which is required for detection of viral RNA by RIGI (PubMed:26746851).PTM (Microbial infection) Deamidated on Asn-495 and Asn-549 by herpes simplex virus 1 protein UL37. These modifications eliminate RIGI detection of viral RNA and restriction of viral replication.PTM Degraded via selective autophagy following interaction with IRGM (PubMed:32715615). IRGM promotes RIGI recruitment to autophagosome membranes, promoting its SQSTM1/p62-dependent autophagic degradation (PubMed:32715615).PTM (Microbial infection) Cleaved by the protease 3C of coxsackievirus B3, poliovirus and enterovirus 71 allowing the virus to disrupt the host type I interferon production.PTM (Microbial infection) Phosphorylated at Ser-8 by herpes simplex virus 1 protein US3 leading to inhibition of critical RIGI activation steps.DISEASE The disease is caused by variants affecting the gene represented in this entry.SIMILARITY Belongs to the helicase family. RLR subfamily.
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