Endonuclease that probably plays a role in the DNA damage response and DNA repair. Interacts (via LEM domain) with BANF1; the interaction may favor BANF1 dimerization. At the steady state, predominantly localizes in the cytoplasm. Predominantly expressed in bone marrow, spleen, thymus, colon and ovary. Expressed also to a lesser extent in lymph nodes, liver and testis. The LEM domain is required for GIY-YIG domain-mediated DNA cleavage and induction of DNA damage response. No visible phenotype. No defect in T cell, B cell and erythrocyte development. Normal percentage of common myeloid precursors (CMP) and common lymphoid precursors (CLP) in the bone marrow. Extended N-terminus. Intron retention.