XRCC6
XRCC6, also known as Ku70, is a DNA-binding protein that is critical for the DNA damage response. With XRCC5 (Ku80) it forms the Ku complex, which binds broken DNA ends and drives repair of double-strand breaks by classical non-homologous end joining. Browse Assay Genie's current range of XRCC6 research reagents below, or read on for the biology behind the target.
XRCC6 is a DNA-binding protein required for repairing double-strand breaks (DSBs) through the classical non-homologous end joining (NHEJ) pathway. It heterodimerises with XRCC5 (Ku80) to form the Ku70:Ku80 complex, which acts as a DNA end-binding complex. The complex primarily binds DSBs and recruits essential repair factors, assembling the core long-range NHEJ complex that aligns and ligates broken DNA ends. This pathway repairs cytotoxic and mutagenic DSBs rapidly and contributes to diversity in T-cell receptors and antibodies through V(D)J recombination.
The XRCC6 protein is annotated as likely acting as a 5'-deoxyribose-5-phosphate lyase, catalysing beta-elimination of the 5'-deoxyribose-5-phosphate at abasic sites near DSBs and so cleaning termini before ligation. It may also have 3'-5' DNA helicase activity, although this has not been confirmed in vivo and its physiological significance is unclear. Beyond repair, it contributes to telomere maintenance and acts as a cofactor for various transcription factors. It also helps assemble the HDP-RNP complex, a platform for IRF3 phosphorylation that activates innate immunity against DNA viruses through the cGAS-STING pathway. It can bind RNAs, recruit PRKDC to cellular RNAs including U3 small nucleolar RNA, and take part in ribosomal RNA biogenesis. It also negatively regulates apoptosis by binding BAX and sequestering it from the mitochondria.
The XRCC6 gene belongs to the Ku70 family and is placed by HGNC in the helicase and DNA-(apurinic or apyrimidinic site) lyase gene groups. Alternative names include Ku70, G22P1, ML8, D22S731 and D22S671, and earlier names include thyroid autoantigen 70kD (Ku antigen). The p70/p80 autoantigen complex is nuclear, and high levels of autoantibodies to p70 and p80 have been found in some patients with systemic lupus erythematosus. The mouse ortholog is Xrcc6.
XRCC6 binds double-strand breaks and recruits repair factors, making it a central protein for studying how cells detect and respond to DNA damage.
As part of the Ku complex, XRCC6 supports end ligation in NHEJ and generates diversity in T-cell receptors and antibodies.
XRCC6 assembles into the HDP-RNP complex that supports IRF3 phosphorylation and activation of the cGAS-STING pathway against DNA viruses.
XRCC6 sequesters BAX from mitochondria to restrain apoptosis and contributes to telomere maintenance, linking repair to cell survival.
XRCC6 (Ku70) binds DNA double-strand breaks as part of the Ku70:Ku80 heterodimer with XRCC5 and recruits factors that assemble the classical NHEJ complex. It also contributes to telomere maintenance, transcription regulation, innate immune signalling and suppression of BAX-mediated apoptosis.
XRCC6 is also called Ku70, with the UniProt name DNA repair protein Ku70. Other aliases and previous symbols are G22P1, ML8, D22S731 and D22S671. Earlier names include thyroid autoantigen 70kD (Ku antigen) and X-ray repair complementing defective repair in Chinese hamster cells 6.
A mouse ortholog, Xrcc6, exists, so the protein can be studied in mouse models; check the datasheet of any product for its validated reactivity. In humans, high levels of autoantibodies to the p70 and p80 Ku subunits have been found in some patients with systemic lupus erythematosus.
XRCC5, the Ku70 heterodimer partner, and other XRCC family DNA repair proteins with products at Assay Genie.
Gene and protein annotations from HGNC, NCBI Gene and UniProt P12956; product specifications from Assay Genie datasheets.