Interferon-induced RNA-binding protein involved in the human innate immune response. Has a broad and adaptable RNA structure recognition important for RNA recognition specificity in antiviral defense. Binds precursor and processed tRNAs as well as poly-U-tailed tRNA fragments (PubMed:25092312, PubMed:23317505, PubMed:23774268). Specifically binds single-stranded RNA bearing a 5'-triphosphate group (PPP-RNA), thereby acting as a sensor of viral single-stranded RNAs. Single-stranded PPP-RNAs, which lack 2'-O-methylation of the 5' cap and bear a 5'-triphosphate group instead, are specific from viruses, providing a molecular signature to distinguish between self and non-self mRNAs by the host during viral infection. Directly binds PPP-RNA in a non-sequence-specific manner (PubMed:23334420). Also recognizes and selectively binds AT-rich dsDNA (PubMed:23774268). Additionally, as a mediator in innate immunity, regulates positively IKK-NFKB signaling by sinergizing the recruitment of IKK to MAP3K7 (PubMed:26334375). Monomer (PubMed:23317505, PubMed:23334420, PubMed:23774268). Interacts with MAP3K7 and the components of the IKK core complex CHUK, IKBKB and IKBKG; the interaction synergizes the recruitment of IKK to MAP3K7 and enhances IKK phosphorylation (PubMed:26334375). Colocalized with DDX58/RIG-I at cell surface ruffles. Localizes to actin-rich protrusions from the apical cell surface. By interferons (IFNs). RNA recognition is mediated by a convoluted intramolecular fold of the TPR repeats (TPR eddy), which scaffolds unique additional helices that form an RNA binding cleft (PubMed:23317505 and PubMed:23334420). Undergoes a conformational change upon RNA-binding: unliganded exists in a more open conformation, facilitating RNA entry (PubMed:23334420). Belongs to the IFIT family.