Required for mRNA export out of the nucleus. Probable RNA helicase that may regulate entry into mitosis by down-regulating the expression of other genes whose activity may be rate-limiting for entry into mitosis during embryogenesis. Binds to salivary gland chromosomes and modifies position effect variegation. Promotes an open chromatin structure that favors transcription during development by regulating the spread of heterochromatin. ATP + H2O = ADP + H(+) + phosphate Component of the spliceosome (Probable). Interacts with the exon junction complex. Locates to nuclei of embryos and ovaries, but disappears in mitotic domains of embryos as chromosomes condense. Expressed both maternally and zygotically. Belongs to the DEAD box helicase family. DECD subfamily.