As an RNA helicase, unwinds RNA and alters RNA structures through ATP binding and hydrolysis. Involved in multiple cellular processes, including pre-mRNA splicing, alternative splicing, ribosomal RNA processing and miRNA processing, as well as transcription regulation. Regulates the alternative splicing of exons exhibiting specific features. This function requires the RNA helicase activity. Affects NFAT5 and histone macro-H2A.1/MACROH2A1 alternative splicing in a CDK9-dependent manner. Affects splicing of mediators of steroid hormone signaling pathway, including kinases that phosphorylates ESR1 and transcriptional regulators. By acting splicing of regulatory factors, participates in ESR1 and AR stabilization. Promotes the inclusion of specific AC-rich alternative exons in CD44 transcripts. In myoblasts and epithelial cells, cooperates with HNRNPH1 to control the splicing of specific subsets of exons. In addition to binding mature mRNAs, also interacts with certain pri-microRNAs, including MIR132/miR-132, and stabilizes the primary transcript. Also participates in the MIR132 processing, resulting in significantly higher levels of mature MIR132 than MIR212 despite the fact that both are cotranscribed and co-regulated (PubMed:26947125). Binding of pri-microRNAs may occur on the 3' segment flanking the stem loop via the 5'-[ACG]CAUC[ACU]-3' consensus sequence (By similarity). Participates in MYC down-regulation at high cell density through the production of MYC-targeting microRNAs. Along with DDX5, may be involved in the processing of the 32S intermediate into the mature 28S rRNA. Promoter-specific transcription regulator, functioning as a coactivator or corepressor depending on the context of the promoter and the transcriptional complex in which it exists. Enhances NFAT5 transcriptional activity. Synergizes with TP53 in the activation of the MDM2 promoter; this activity requires acetylation on lysine residues. May also coactivate MDM2 transcription through a TP53-independent pathway. Coactivates MMP7 transcription. Along with CTNNB1, coactivates MYC, JUN, FOSL1 and cyclin D1/CCND1 transcription. Alone or in combination with DDX5 and/or SRA1 non-coding RNA, plays a critical role in promoting the assembly of proteins required for the formation of the transcription initiation complex and chromatin remodeling leading to coactivation of MYOD1-dependent transcription. This helicase-independent activity is required for skeletal muscle cells to properly differentiate into myotubes (PubMed:17011493). During epithelial-to-mesenchymal transition, coregulates SMAD-dependent transcriptional activity, directly controlling key effectors of differentiation, including miRNAs which in turn directly repress its expression. Plays a role in estrogen and testosterone signaling pathway at several levels. Mediates the use of alternative promoters in estrogen-responsive genes and regulates transcription and splicing of a large number of steroid hormone target genes. Contrary to the splicing regulation activity, transcriptional coregulation of the estrogen receptor ESR1 is helicase activity-independent. Plays a role in innate immunity. Specifically restricts bunyavirus infection, including Rift Valley fever virus (RVFV) or La Crosse virus (LACV), but not vesicular stomatitis virus (VSV), in an interferon- and DROSHA-independent manner. Binds to RVFV RNA, likely via structured viral RNA elements (By similarity). Promotes mRNA degradation mediated by the antiviral zinc-finger protein ZC3HAV1, in an ATPase-dependent manner (By similarity). ATP + H2O = ADP + H(+) + phosphate Interacts with DDX5 in an RNA-independent manner (By similarity). Interacts with CDK9 transcription elongation complex under basal conditions. Following cell stimulation with poly(I:C), a synthetic double-stranded RNA mimicking viral infection, the interaction with CDK9 is decreased (By similarity). Interacts with ESR1 in an estrogen-independent manner (By similarity). Interacts with HNRNPH1; this interaction is important for the regulation of alternative splicing on G-quadruplex structures (By similarity). At high, but not low, cell density, interacts with DROSHA and DGCR8, the core components of the microprocessor complex involved in the maturation of primary microRNAs (pri-miRNAs) into pre-miRNAs. The interaction with DGCR8 is reduced during mitosis. At low, but not high, cell density, interacts with YAP1 and with its paralog, WWTR1/TAZ. Interactions with DROSHA and YAP1 are mutually exclusive. In vitro, the pre-miRNA processing activity of the DDX17-containing microprocessor complex is weaker than that of the DROSHA/DGCR8 microprocessor complex (By similarity). Interacts with UPF3B (By similarity). Interacts with NFAT5; this interaction leads to DDX17 recruitment to LNC2 and S100A4 promoters and NFAT5-mediated DDX17-enhanced transactivation (By similarity). Interacts with HDAC1, HDAC2 and HDAC3; this interaction with HDAC1 and HDAC3, but not HDAC2, depends upon DDX17 acetylation (By similarity). Interacts with ZC3HAV1 (via N-terminal domain) in an RNA-independent manner. Interacts with EXOSC3/RRP40 and EXOSC5/RRP46; this interaction may be indirect and mediated by ZC3HAV1-binding (By similarity). Interacts with EP300; this interaction leads to acetylation at lysine residues (By similarity). Interacts with CREBBP/CBP and KAT2B/P/CAF (By similarity). Directly interacts with CTNNB1 (By similarity). Interacts with MYOD1 (PubMed:17011493). Interacts with TP53 (By similarity). Interacts with DCP1A in an RNA-independent manner. Interacts with DCP2 in an RNA-dependent manner (By similarity). Interacts with DHX36; this interaction occurs in a RNA-dependent manner (By similarity). Interacts with ERCC6 (By similarity). In the course of bunyavirus infection, relocalizes from the nucleus to the cytosol where it binds viral RNA to antagonize replication. Sumoylation significantly increases stability. It also promotes interaction specifically with HDAC1 (but not HDAC2, nor HDAC3) and strongly stimulates ESR1 and TP53 coactivation. Acetylation at lysine residues stabilizes the protein, stimulates interaction with HDAC1 and HDAC3, but not HDAC2, and represses ESR1 and TP53 coactivation activity. Belongs to the DEAD box helicase family. DDX5/DBP2 subfamily.