ATP-binding RNA helicase involved in translation initiation. Remodels RNA in response to ADP and ATP concentrations by facilitating disruption, but also formation of RNA duplexes (By similarity). Inactivation of ded1 blocks mitotic cell cycle progression at G1 and G2/M. Induces sexual development and ascus formation. ATP + H2O = ADP + H(+) + phosphate Interacts with chk1, which is required for cell cycle arrest following DNA damage. The Q motif is unique to and characteristic of the DEAD box family of RNA helicases and controls ATP binding and hydrolysis. A different form of ded1 has been identified via SDS-PAGE studies. It is uncertain how this form arises in vivo. Belongs to the DEAD box helicase family. DDX3/DED1 subfamily.