IFN-induced antiviral protein which inhibits expression of viral messenger RNAs lacking 2'-O-methylation of the 5' cap. The ribose 2'-O-methylation would provide a molecular signature to distinguish between self and non-self mRNAs by the host during viral infection. Viruses evolved several ways to evade this restriction system such as encoding their own 2'-O-methylase for their mRNAs or by stealing host cap containing the 2'-O-methylation (cap snatching mechanism). Binds AU-rich viral RNAs, with or without 5' triphosphorylation, RNA-binding is required for antiviral activity. Can promote apoptosis. Domain-swapped homodimer. Component of an interferon-dependent multiprotein complex, at least composed of IFIT1, IFIT2 and IFIT3. Interacts with IFIT1 and IFIT3. Interacts with STING1/MITA and disrupts its interaction with MAVS or TBK1. Interacts with EIF3E and EIF3C. By type I interferons, dsRNAs and viruses. The C-terminal part folds into a super-helical structure and has an extensively positively-charged nucleotide-binding channel on its inner surface. Belongs to the IFIT family.