XRCC6 Antibody – Rabbit Polyclonal

The p70/p80 autoantigen is a nuclear complex consisting of two subunits with molecular masses of approximately 70 and 80 kDa. The 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. High levels of autoantibodies to p70 and p80 have been found in some patients with systemic lupus erythematosus. [provided by RefSeq, Jul 2008]

Function: Single-stranded DNA-dependent ATP-dependent helicase. Has a role in chromosome translocation. The DNA helicase II complex binds preferentially to fork-like ends of double-stranded DNA in a cell cycle-dependent manner. It works in the 3'-5' direction. Binding to DNA may be mediated by XRCC6. Involved in DNA non-homologous end joining (NHEJ) required for double-strand break repair and V(D)J recombination. The XRCC5/6 dimer acts as regulatory subunit of the DNA-dependent protein kinase complex DNA-PK by increasing the affinity of the catalytic subunit PRKDC to DNA by 100-fold. The XRCC5/6 dimer is probably involved in stabilizing broken DNA ends and bringing them together. The assembly of the DNA-PK complex to DNA ends is required for the NHEJ ligation step. Required for osteocalcin gene expression. Probably also acts as a 5'-deoxyribose-5-phosphate lyase (5'-dRP lyase), by catalyzing the beta-elimination of the 5' deoxyribose-5-phosphate at an abasic site near double-strand breaks. 5'-dRP lyase activity allows to 'clean' the termini of abasic sites, a class of nucleotide damage commonly associated with strand breaks, before such broken ends can be joined. The XRCC5/6 dimer together with APEX1 acts as a negative regulator of transcription. Ref.2 Ref.10 Ref.12 Ref.14 Ref.19 Ref.26 Ref.27

Subunit structure: Heterodimer of a 70 kDa (XRCC6) and a 80 kDa (XRCC5) subunit. The dimer 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. In addition, XRCC6 interacts with the osteoblast-specific transcription factors MSX2, RUNX2 and DLX5. Interacts with ELF3. Interacts with XRCC6BP1. The XRCC5/6 dimer associates in a DNA-dependent manner with APEX1. Interacts with CLU

By similarity. Binds to CDK9 isoform 2. Identified in a complex with DEAF1 and XRCC5. Interacts with DEAF1 (via the SAND domain); the interaction is direct and may be inhibited by DNA-binding. Ref.10 Ref.14 Ref.17 Ref.18 Ref.19 Ref.20 Ref.21 Ref.26 Ref.31

Subcellular location: Nucleus. Chromosome Ref.31.

Developmental stage: Expression does not increase during promyelocyte differentiation. Ref.9

Induction: In osteoblasts, by FGF2.

Post-translational modification: Phosphorylation by PRKDC may enhance helicase activity. Phosphorylation of Ser-51 does not affect DNA repair.

Miscellaneous: Individuals with systemic lupus erythematosus (SLE) and related disorders produce extremely large amounts of autoantibodies to XRCC5 and XRCC6. Existence of a major autoantigenic epitope or epitopes on the C-terminal 190 amino acids of XRCC6 containing the leucine repeat. The majority of autoantibodies to XRCC6 in most sera from patients with SLE seem to be reactive with this region.

Sequence similarities: Belongs to the ku70 family.Contains 1 Ku domain.Contains 1 SAP domain.