ATP-dependent RNA helicase involved in mRNA export from the nucleus. Rather than unwinding RNA duplexes, DDX19 functions as a remodeler of ribonucleoprotein particles, whereby proteins bound to nuclear mRNA are dissociated and replaced by cytoplasmic mRNA binding proteins. ATP + H2O = ADP + H(+) + phosphate Associates with the nuclear pore complex cytoplasmic fibrils. The N-terminal extension helix acts as an autoinhibitory domain, preventing ATP hydrolysis, unless the N-terminus of the protein is displaced by RNA binding, allowing cleft closure to bring key side chains into position for catalysis. Belongs to the DEAD box helicase family. DDX19/DBP5 subfamily.