ATP- and magnesium-dependent helicase that plays an essential role in innate immunity (PubMed:30510222). Participates in the DNA-triggered cGAS/STING pathway by promoting the DNA binding and activation of CGAS. Enhances also DDX58-induced type I interferon production probably by helping DDX58 at sensing pathogenic RNA (PubMed:30804210). In addition, plays an essential role in stress granule formation (PubMed:12642610, PubMed:20180778, PubMed:23279204). Unwinds preferentially partial DNA and RNA duplexes having a 17 bp annealed portion and either a hanging 3' tail or hanging tails at both 5'- and 3'-ends (PubMed:9889278). Unwinds DNA/DNA, RNA/DNA, and RNA/RNA substrates with comparable efficiency (PubMed:9889278). Acts unidirectionally by moving in the 5' to 3' direction along the bound single-stranded DNA (PubMed:9889278). Phosphorylation-dependent sequence-specific endoribonuclease in vitro (PubMed:11604510). Cleaves exclusively between cytosine and adenine and cleaves MYC mRNA preferentially at the 3'-UTR (PubMed:11604510). ATP + H2O = ADP + H(+) + phosphate ATP + H2O = ADP + H(+) + phosphate Mg(2+) is required for helicase activity. Homodimer and oligomer (PubMed:12642610, PubMed:24324649). Component of a TAU mRNP complex, at least composed of IGF2BP1, ELAVL4 and G3BP1 (By similarity). Binds to the SH3 domain of Ras GTPase-activating protein (RASA1) in proliferating cells (By similarity). No interaction in quiescent cells (By similarity). Interacts (via NTF2-like domain) with USP10 (PubMed:11439350, PubMed:23279204). Interacts with RPTOR and SPAG5; this complex is increased by oxidative stress (PubMed:23953116). Interacts with ATXN2L (PubMed:23209657). Interacts with STYXL1 (PubMed:20180778). Interacts with CGAS (via N-terminus); this interaction promotes the DNA-binding and activation of CGAS (PubMed:30510222). Interacts (via C-terminus) with DDX58 (PubMed:30804210). Interacts (via NTF2-like domain) with CAPRIN1 (PubMed:17210633). Interacts with PABPC1 (PubMed:23279204). (Microbial infection) Interacts with Semliki forest virus non-structural protein 3 (via C-terminus); this interaction inhibits the formation of host stress granules on viral mRNAs and the nsp3-G3BP1 complexes bind viral RNAs and probably orchestrate the assembly of viral replication complexes. (Microbial infection) Interacts with Chikungunya virus non-structural protein 3 (via C-terminus); this interaction inhibits the formation of host stress granules on viral mRNAs and the nsp3-G3BP1 complexes bind viral RNAs and probably orchestrate the assembly of viral replication complexes. (Microbial infection) Interacts with Sindbis virus non-structural protein 3 (via C-terminus); this interaction inhibits the formation of host stress granules on viral mRNAs and the nsp3-G3BP1 complexes bind viral RNAs and probably orchestrate the assembly of viral replication complexes. Cytoplasmic in proliferating cells (PubMed:11604510). Cytosolic and partially nuclear in resting cells (PubMed:11604510). Recruited to stress granules in response to arsenite treatment (PubMed:12642610, PubMed:20180778). The unphosphorylated form is recruited to stress granules (PubMed:12642610). HRAS signaling contributes to this process by regulating G3BP dephosphorylation (PubMed:12642610). Ubiquitous. The NTF2 domain mediates multimerization. (Microbial infection) Cleaved by human enterovirus 71; this cleavage induces the disassembly of cytoplasmic stress granules (PubMed:30006004). Cleaved by Foot-and-mouth disease virus; this cleavage suppresses the formation of cytoplasmic stress granules (PubMed:30404792). Phosphorylated exclusively on serine residues. Hyperphosphorylated in quiescent fibroblasts. Hypophosphorylation leads to a decrease in endoribonuclease activity (By similarity). RASA1-dependent phosphorylation of Ser-149 induces a conformational change that prevents self-association. Dephosphorylation after HRAS activation is required for stress granule assembly. Ser-149 phosphorylation induces partial nuclear localization. Arg-435 is dimethylated, probably to asymmetric dimethylarginine.