Figure 4.

Model for involvement of poly(ADP‐ribose) polymerase (PARP) in DNA repair. DNA damage directly produces base damage, single‐strand breaks (SSB) and double‐strand breaks (DSB). SSB may be left unligated accidentally in the process of base excision repair (BER). SSB are possibly converted to DSB in a replication‐mediated manner or replication‐independently. Involvement of PARP in short‐patch and long‐patch repairs of BER, non‐homologous end‐joining (NHEJ) repair, and homologous recombination (HR) repair is shown. FEN1, flap endonuclease I; LIG, DNA ligase; PCNA, proliferating cell nuclear antigen; PNK, polynucleotide kinase; POL, DNA polymerase.