Antiviral protein which inhibits the replication of viruses by recruiting the cellular RNA degradation machineries to degrade the viral mRNAs. Binds to a ZAP-responsive element (ZRE) present in the target viral mRNA, recruits cellular poly(A)-specific ribonuclease PARN to remove the poly(A) tail, and the 3'-5' exoribonuclease complex exosome to degrade the RNA body from the 3'-end. It also recruits the decapping complex DCP1-DCP2 through RNA helicase p72 (DDX17) to remove the cap structure of the viral mRNA to initiate its degradation from the 5'-end. Its target viruses belong to families which include retroviridae: human immunodeficiency virus type 1 (HIV-1), moloney and murine leukemia virus (MoMLV) and xenotropic MuLV-related virus (XMRV), filoviridae: ebola virus (EBOV) and marburg virus (MARV), togaviridae: sindbis virus (SINV) and Ross river virus (RRV). Specifically targets the multiply spliced but not unspliced or singly spliced HIV-1 mRNAs for degradation. Isoform 1 is a more potent viral inhibitor than isoform 2. Isoform 2 acts as a positive regulator of DDX58/RIG-I signaling resulting in activation of the downstream effector IRF3 leading to the expression of type I IFNs and IFN stimulated genes (ISGs). Thermostable. Homodimer or homooligomer. Homooligomerization is essential for its antiviral activity. Interacts with EXOSC5 (By similarity). Interacts (via N-terminal domain) with DDX17 in an RNA-independent manner (By similarity). Interacts with EXOSC3, EXOSC7, DCP2 and DCP1A. Interacts with PARN in an RNA-independent manner. Interacts with XRN1 in an RNA-dependent manner. Isoform 2 interacts (via zinc-fingers) with DDX58/RIG-I in an RNA-dependent manner. Interacts (via N-terminal domain) with DHX30 (via N-terminus) in an RNA-independent manner. Localizes in the cytoplasm at steady state, but shuttles between nucleus and cytoplasm in a XPO1-dependent manner. By type I interferon (IFN) and viruses. Isoform 2 is up-regulated by 3'-PPP-RNA. The N-terminal domain is sufficient to bind to viral RNAs and promote their degradation. The second and fourth zinc fingers are involved in binding to specific viral RNAs (PubMed:20451500). Contains a divergent PARP homology ADP-ribosyltransferase domain which lacks the structural requirements for NAD[+] binding (PubMed:25635049). It is therefore inactive (PubMed:25043379, PubMed:25635049). Phosphorylation at Ser-275 is essential for sequential phosphorylation of Ser-271, Ser-267, Ser-263 and Ser-257 by GSK3-beta. Phosphorylation by GSK3-beta enhances its antiviral activity (By similarity). Belongs to the ARTD/PARP family.