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 (PubMed:23093941). Plays an important role in innate antiviral immunity by promoting type I interferon production (PubMed:27016603, PubMed:35157734, PubMed:27974568). Mechanistically, specifically uses IKKepsilon/IKBKE as the mediator kinase for IRF3 activation (PubMed:27016603, PubMed:35157734). Blocks HIV-1 virus replication at a post-entry step (PubMed:20215113). Counteracts HIV-1 Vif-mediated degradation of APOBEC3G through its helicase activity by interfering with the ubiquitin-proteasome pathway (PubMed:29258557). Inhibits also hepatitis B virus/HBV replication by interacting with HBV RNA and thereby inhibiting the early step of viral reverse transcription (PubMed:31722967). Contributes to UPF1 mRNA target degradation by translocation along 3' UTRs (PubMed:24726324). 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 (PubMed:16289642, PubMed:17507929, PubMed:22791714). In cooperation with FMR1, regulates miRNA-mediated translational repression by AGO2 (PubMed:25464849). Restricts retrotransposition of long interspersed element-1 (LINE-1) in cooperation with TUT4 and TUT7 counteracting the RNA chaperonne activity of L1RE1 (PubMed:30122351, PubMed:23093941). Facilitates LINE-1 uridylation by TUT4 and TUT7 (PubMed:30122351). 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 (PubMed:24726324). (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. ATP + H2O = ADP + H(+) + phosphate Interacts with DICER1, AGO2, TARBP2, EIF6 and RPL7A (60S ribosome subunit); they form a large RNA-induced silencing complex (RISC) (PubMed:17507929). Interacts with APOBEC3G in an RNA-dependent manner. Interacts with TRIM71 (via NHL repeats) in an RNA-dependent manner (PubMed:23125361). Interacts with both protein products of LIRE1, ORF1p and ORF2p (PubMed:23093941). Interacts with TUT4 and, to a lesser extent, TUT7; the interactions are RNA-dependent (PubMed:30122351). Interacts with AGO2, TNRC6B and UPF1; the interactions are direct and RNA-dependent (PubMed:24726324). Interacts with FMR1; this interaction is direct, occurs in an RNA-dependent manner on polysomes and induces association of MOV10 with RNAs (PubMed:25464849). Interacts with SHFL; the interaction increases in presence of RNA (PubMed:27974568). Interacts with DHX34; the interaction is RNA-independent (PubMed:25220460). Interacts with IKBKE (PubMed:27016603, PubMed:35157734). (Microbial infection) Interacts with the human hepatitis delta virus (HDV) antigen HDAg. (Microbial infection) Interacts with HIV-1 protein GAG. Co-enriched in cytoplasmic foci with TUT4 (PubMed:30122351). 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 (PubMed:27974568). By herpes simplex 1/HHV-1 virus infection. (Microbial infection) Cleaved and targeted for degradation by picornavirus proteases. Belongs to the DNA2/NAM7 helicase family. SDE3 subfamily. Wrong choice of CDS. Extended N-terminus.