DNA-PK, active

DNA-PK is a serine/threonine-protein kinase that acts as a molecular sensor for DNA damage. Involved in DNA non-homologous end joining (NHEJ) required for double-strand break (DSB) repair and V(D)J recombination. Must be bound to DNA to express its catalytic properties. Promotes processing of hairpin DNA structures in V(D)J recombination by activation of the hairpin endonuclease artemis (DCLRE1C). Recruited by XRCC5 and XRCC6 to DNA ends and is required to protect and align broken ends of DNA, thereby preventing their degradation, and sequester the DSB for repair by NHEJ. Act as a scaffold protein to aid the localization of DNA repair proteins to the site of damage. The assembly of the DNA-PK complex at DNA ends is also required for the NHEJ ligation step. Found at the ends of chromosomes, suggesting a further role in the maintenance of telomeric stability and the prevention of chromosomal end fusion (By similarity). Also involved in modulation of transcription.