Ku80 is the 80 kDa subunit of the lupus Ku autoantigen. The lupus Ku autoantigen was identified in individuals with systemic lupus erythematosus (SLE) and related disorders. The Ku antigen is a heterodimer of Ku70 and Ku80. The Ku70/Ku80 complex functions as a single-stranded DNA-dependent ATP-dependent helicase. The complex may be involved in the repair of nonhomologous DNA ends such as that required for double-strand break repair, transposition, and V(D)J recombination [taken from the Universal Protein Resource (UniProt) www.uniprot.org/uniprot/P13010].