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DEXXQ-box helicase domain of DNA2 DNA2 (DNA Replication Helicase/Nuclease 2) possesses different enzymatic activities, such as single-stranded DNA (ssDNA)-dependent ATPase, 5-3 helicase, and endonuclease activities, and is involved in DNA replication and DNA repair in the nucleus and mitochondrion. It is involved in Okazaki fragment processing by cleaving long flaps that escape FEN1: flaps that are longer than 27 nucleotides are coated by replication protein A complex (RPA), leading to recruit DNA2 which cleaves the flap until it is too short to bind RPA and becomes a substrate for FEN1. It is also involved in 5-end resection of DNA during double-strand break (DSB) repair; it is recruited by BLM and mediates the cleavage of 5-ssDNA, while the 3-ssDNA cleavage is prevented by the presence of RPA. DNA2 is a member of the DEAD-like helicase superfamily, a diverse family of proteins involved in ATP-dependent RNA or DNA unwinding. This domain contains the ATP-binding region.
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