XRCC4: Involved in DNA non-homologous end joining (NHEJ) required for double-strand break repair and V(D)J recombination. Binds to DNA and to DNA ligase IV (LIG4). The LIG4-XRCC4 complex is responsible for the NHEJ ligation step, and XRCC4 enhances the joining activity of LIG4. Binding of the LIG4-XRCC4 complex to DNA ends is dependent on the assembly of the DNA-dependent protein kinase complex DNA-PK to these DNA ends. Homodimer and homotetramer in solution. The homodimer associates with LIG4, and the LIG4-XRCC4 complex associates in a DNA-dependent manner with the DNA-PK complex formed by the Ku p70/p86 dimer (XRCC6/XRCC5) and PRKDC. Seems to interact directly with PRKDC but not with the Ku p70/86 dimer. Interacts with XLF/Cernunnos. Interacts with APTX and APLF. Widely expressed. Belongs to the XRCC4 family. 3 isoforms of the human protein are produced by alternative splicing.
Protein type: DNA repair, damage
Chromosomal Location of Human Ortholog: 5q14.2
Cellular Component: nucleoplasm; DNA ligase IV complex; centrosome; condensed chromosome; DNA-dependent protein kinase complex; cell junction; cytosol; nucleus
Molecular Function: protein C-terminus binding; protein binding; DNA binding; ligase activity
Biological Process: pro-B cell differentiation; positive regulation of neurogenesis; central nervous system development; viral reproduction; immunoglobulin V(D)J recombination; in utero embryonic development; isotype switching; T cell differentiation in the thymus; DNA repair; double-strand break repair via nonhomologous end joining; positive regulation of fibroblast proliferation; double-strand break repair; response to gamma radiation; DNA ligation during DNA repair; negative regulation of neuron apoptosis; positive regulation of ligase activity; response to X-ray
Disease: Short Stature, Microcephaly, And Endocrine Dysfunction
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