5' to 3' RNA helicase that is involved in a number of cellular roles ranging from mRNA metabolism and translation, modulation of viral infectivity, inhibition of retrotransposition, or regulation of synaptic transmission . Plays an important role in innate antiviral immunity by promoting type I interferon production ( ). Mechanistically, specifically uses IKKepsilon/IKBKE as the mediator kinase for IRF3 activation (, ). Blocks HIV-1 virus replication at a post-entry step . Counteracts HIV-1 Vif-mediated degradation of APOBEC3G through its helicase activity by interfering with the ubiquitin-proteasome pathway . Inhibits also hepatitis B virus/HBV replication by interacting with HBV RNA and thereby inhibiting the early step of viral reverse transcription . Contributes to UPF1 mRNA target degradation by translocation along 3' UTRs . Required for microRNA (miRNA)-mediated gene silencing by the RNA-induced silencing complex (RISC). Required for both miRNA-mediated translational repression and miRNA-mediated cleavage of complementary mRNAs by RISC ( ). In cooperation with FMR1, regulates miRNA-mediated translational repression by AGO2 . Restricts retrotransposition of long interspersed element-1 (LINE-1) in cooperation with TUT4 and TUT7 counteracting the RNA chaperonne activity of L1RE1 (, ). Facilitates LINE-1 uridylation by TUT4 and TUT7 . Required for embryonic viability and for normal central nervous system development and function. Plays two critical roles in early brain development: suppresses retroelements in the nucleus by directly inhibiting cDNA synthesis, while regulates cytoskeletal mRNAs to influence neurite outgrowth in the cytosol (By similarity). May function as a messenger ribonucleoprotein (mRNP) clearance factor .
(Microbial infection) Required for RNA-directed transcription and replication of the human hepatitis delta virus (HDV). Interacts with small capped HDV RNAs derived from genomic hairpin structures that mark the initiation sites of RNA-dependent HDV RNA transcription.
Subcellular locations: Cytoplasm, P-body, Cytoplasm, Cytoplasmic ribonucleoprotein granule, Cytoplasm, Stress granule, Nucleus, Cytoplasm
Co-enriched in cytoplasmic foci with TUT4 . In developing neurons, localizes both in nucleus and cytoplasm, but in the adulthood it is only cytoplasmic (By similarity). After infection, relocalizes to the DENV replication complex in perinuclear regions .