ATP-dependent chromatin-remodeling factor which functions as substrate recognition component of the transcription regulatory histone acetylation (HAT) complex SAGA. Regulates polymerase II transcription. Also required for efficient transcription by RNA polymerase I, and more specifically the polymerase I transcription termination step. Regulates negatively DNA replication. Not only involved in transcription-related chromatin remodeling, but also required to maintain a specific chromatin configuration across the genome (By similarity). Involved in assembly of active chromatin. Required for maintaining open chromatin and pluripotency in embryonic stem cells and is important for wing development and fertility. Is essential for the incorporation of histone H3.3 and assembly of paternal chromatin. Required for replication-independent nucleosome assembly in the decondensing male pronucleus. ATP + H2O = ADP + H(+) + phosphate Component of the SAGA complex (By similarity). Interacts with SSRP1. Colocalizes with elongating RNA polymerase II (Pol II) on polytene chromosomes (PubMed:18202396). Belongs to the SNF2/RAD54 helicase family.