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Ku-core domain; includes the central DNA-binding beta-barrels, polypeptide rings, and the C-terminal arm of Ku proteins. The Ku protein consists of two tightly associated homologous subunits, Ku70 and Ku80, and was originally identified as an autoantigen recognized by the sera of patients with an autoimmunity disease. In eukaryotes, the Ku heterodimer contributes to genomic integrity through its ability to bind DNA double-strand breaks and facilitate repair by non-homologous end-joining. The bacterial Ku homologs does not contain the conserved N-terminal extension that is present in the eukaryotic Ku protein.
Jiyao W et al.(2023). "The conserved domain database in 2023.",