RNA helicase involved in mRNA processing and antiviral innate immunity (PubMed:19432882, PubMed:19103666, PubMed:32179686, PubMed:24990078, PubMed:24782566, PubMed:34161762). Pre-mRNA processing factor involved in disassembly of spliceosomes after the release of mature mRNA (PubMed:19103666). In cooperation with TFIP11 seem to be involved in the transition of the U2, U5 and U6 snRNP-containing IL complex to the snRNP-free IS complex leading to efficient debranching and turnover of excised introns (PubMed:19103666). Plays a key role in antiviral innate immunity by promoting both MAVS-dependent signaling and NLRP6 inflammasome (PubMed:24990078, PubMed:24782566, PubMed:34161762). Acts as an RNA virus sensor: recognizes and binds viral double stranded RNA (dsRNA) and activates the MAVS-dependent signaling to produce interferon-beta and interferon lambda-3 (IFNL3) (PubMed:24990078, PubMed:24782566, PubMed:34161762). Involved in intestinal antiviral innate immunity together with NLRP6: recognizes and binds viral dsRNA and promotes activation of the NLRP6 inflammasome in intestinal epithelial cells to restrict infection by enteric viruses (PubMed:34161762). The NLRP6 inflammasome acts by promoting maturation and secretion of IL18 in the extracellular milieu (PubMed:34161762). Also involved in antibacterial innate immunity by promoting Wnt-induced antimicrobial protein expression in Paneth cells (By similarity). ATP + H2O = ADP + H(+) + phosphate ATPase activity is enhanced upon binding to G-patch domain-containing proteins (PubMed:32179686). G-patch domain-containing proteins act like a brace that tethers mobile sections of DHX15 together, stabilizing a functional conformation with high RNA affinity, thereby promoting the ATPase activity (PubMed:32179686). Component of the U11/U12 snRNPs that are part of the U12-type spliceosome (PubMed:15146077). Identified in the Intron Large spliceosome complex (IL, also named intron lariat spliceosome), a post-mRNA release spliceosomal complex containing the excised intron, U2, U5 and U6 snRNPs, and splicing factors; the association may be transient (PubMed:19103666, PubMed:30728453). The IL complex exists in two distinct conformations, one with the DHX15 (ILS2) and one without (ILS1) (PubMed:30728453). Interacts with TFIP11 (via G-patch domain); indicative for a recruitment to the IL complex (PubMed:19103666). Interacts with SSB/La (PubMed:12458796). Interacts with GPATCH2 (via G-patch domain); promoting the RNA helicase activity (PubMed:19432882). Interacts with NKRF (via G-patch domain); promoting the RNA helicase activity (PubMed:32179686). Interacts with NLRP6 (PubMed:34161762). Ubiquitous. Belongs to the DEAD box helicase family. DEAH subfamily. DDX15/PRP43 sub-subfamily.