Acts as an ATP-dependent RNA helicase, able to unwind both RNA-RNA and RNA-DNA duplexes. Possesses 5' single-stranded RNA overhang nuclease activity. Acts as a positive regulator of transcription. May be involved in 3'-end cleavage and polyadenylation of pre-mRNAs. Binds DNA and RNA. Component of the tRNA-splicing ligase complex required to facilitate the enzymatic turnover of catalytic subunit rtcb. Binds (via helicase ATP-binding domain) on both short and long poly(I:C) dsRNA (By similarity). ATP + H2O = ADP + H(+) + phosphate The helicase domain is involved in the stimulation of RELA transcriptional activity. Belongs to the DEAD box helicase family. DDX1 subfamily.