Interferon-inducible antiviral protein which plays a major role in the cell antiviral state induced by type I and type II interferon . Catalyzes the conversion of cytidine triphosphate (CTP) to 3'-deoxy-3',4'-didehydro-CTP (ddhCTP) via a SAM-dependent radical mechanism (, ). In turn, ddhCTP acts as a chain terminator for the RNA-dependent RNA polymerases from multiple viruses and directly inhibits viral replication . Therefore, inhibits a wide range of DNA and RNA viruses, including human cytomegalovirus (HCMV), hepatitis C virus (HCV), west Nile virus (WNV), dengue virus, sindbis virus, influenza A virus, sendai virus, vesicular stomatitis virus (VSV), zika virus, and human immunodeficiency virus (HIV-1) ( , ). Promotes also TLR7 and TLR9-dependent production of IFN-beta production in plasmacytoid dendritic cells (pDCs) by facilitating 'Lys-63'-linked ubiquitination of IRAK1 by TRAF6 . Plays a role in CD4+ T-cells activation and differentiation. Facilitates T-cell receptor (TCR)-mediated GATA3 activation and optimal T-helper 2 (Th2) cytokine production by modulating NFKB1 and JUNB activities. Can inhibit secretion of soluble proteins.
Subcellular locations: Endoplasmic reticulum membrane, Golgi apparatus, Endoplasmic reticulum, Lipid droplet, Mitochondrion, Mitochondrion inner membrane, Mitochondrion outer membrane
Infection with human cytomegalovirus (HCMV) causes relocation to the Golgi apparatus and to cytoplasmic vacuoles which also contain HCMV proteins glycoprotein B and pp28. Interaction with human cytomegalovirus/HHV-5 protein vMIA/UL37 results in its relocalization from the endoplasmic reticulum to the mitochondria.