Interacts with EME1 to form a DNA structure-specific endonuclease with substrate preference for branched DNA structures with a 5'-end at the branch nick. Typical substrates include 3'-flap structures, D-loops, replication forks, nicked Holliday junctions and also intact Holliday junctions with a reduced efficiency. May be required in mitosis for the processing of stalled or collapsed replication fork intermediates. Plays a role in DNA repair and in genotoxic stress-induced homologous recombination (HR) in somatic cells. Mediates a subset of meiotic recombination events that are insensitive to crossover interference (By similarity). Forms a heterodimer with EME1 (By similarity). Interacts with RAD54. Low expression in shoots and roots from etiolated seedlings, and panicles after meiosis; moderate expression in young panicles under differentiation of floral organs before and during meiosis; and high expression in mature leaves. By DNA-damaging treatments such as high intensity light, UV-C and gamma-radiation. Belongs to the XPF family.