Enables ATP binding activity; DNA binding activity; and DNA ligase (ATP) activity. Involved in DNA ligation and cellular response to lithium ion. Located in nucleus. Human ortholog(s) of this gene implicated in several diseases, including DNA ligase IV deficiency; colorectal cancer; high grade glioma; multiple myeloma; and prostate cancer. Orthologous to human LIG4 (DNA ligase 4). [provided by Alliance of Genome Resources, Apr 2022]