Probable adapter protein involved in different biological processes (PubMed:22427340, PubMed:27194766). Part of the signaling pathways that lead to apoptosis (PubMed:18330707, PubMed:27673746, PubMed:24970806). Involved in type-I interferon-induced apoptosis characterized by a rapid and robust release of cytochrome C from the mitochondria and activation of BAX and caspases 2, 3, 6, 8 and 9 (PubMed:18330707, PubMed:27673746). Also functions in TNFSF10-induced apoptosis (PubMed:24970806). May also have a function in the nucleus, where it may be involved in the interferon-induced negative regulation of the transcriptional activity of NR4A1, NR4A2 and NR4A3 through the enhancement of XPO1-mediated nuclear export of these nuclear receptors (PubMed:22427340). May thereby play a role in the vascular response to injury (By similarity). In the innate immune response, has an antiviral activity towards hepatitis C virus/HCV (PubMed:27194766, PubMed:27777077). May prevent the replication of the virus by recruiting both the hepatitis C virus non-structural protein 5A/NS5A and the ubiquitination machinery via SKP2, promoting the ubiquitin-mediated proteasomal degradation of NS5A (PubMed:27194766, PubMed:27777077). Homodimer (PubMed:27673746). Interacts with hepatitis C virus/HCV non-structural protein NS5A; promotes the ubiquitin-mediated proteasomal degradation of NS5A (PubMed:27194766). Interacts with SKP2; promotes the ubiquitin-mediated proteasomal degradation of NS5A (PubMed:27194766). Interacts with NR4A1 (PubMed:22427340). May interact with BCL2 (PubMed:27673746). Exclusive localizations in either the nucleus or the mitochondrion have been reported. Up-regulated by type-I and type-II interferons. Major isoform in blood and cervix. Belongs to the IFI6/IFI27 family.