X-ray repair cross-complementing protein 5, also known as 86 kDa subunit of Ku antigen, ATP-dependent DNA helicase 2 subunit 2, ATP-dependent DNA helicase II 80 kDa subunit, CTC box-binding factor 85 kDa subunit, DNA repair protein XRCC5, Lupus Ku autoantigen protein p86, TLAA and XRCC5, is a nucleus and chromosome which belongs to the ku80 family. XRCC5 is a single stranded DNA-dependent ATP-dependent helicase. XRCC5 has a role in chromosome translocation.  X-ray repair cross-complementing protein 6, also known as 5'-deoxyribose-5-phosphate lyase Ku70, ATP-dependent DNA helicase 2 subunit 1, ATP-dependent DNA helicase II 70 kDa subunit, 70 kDa subunit of Ku antigen, ATP-dependent DNA helicase 2 subunit 1, CTC box-binding factor 75 kDa subunit, Lupus Ku autoantigen protein p70, Thyroid-lupus autoantigen and XRCC6, is a nucleus and chromosome which belongs to the ku70 family. Heterodimer of a XRCC6 and a XRCC5 subunit associates in a DNA-dependent manner with PRKDC to form the DNA-dependent protein kinase complex DNA-PK, and with the LIG4-XRCC4 complex. The dimer also associates with NAA15, and this complex binds to the osteocalcin promoter and activates osteocalcin expression.