DsDNA-dependent ATPase which acts as a transcription termination factor by coupling ATP hydrolysis with removal of RNA polymerase II from the DNA template. May contribute to mitotic transcription repression. May also be involved in pre-mRNA splicing. Interacts with CDC5L. Part of the spliceosome. Cytoplasmic during interphase. Relocates to the nucleus as cells enter mitosis. Belongs to the SNF2/RAD54 helicase family.