ADP-ribosylation
（重定向自ADP ribosylation）
![ADP ribose](/Images/godic/202412/20/ADP_ribose.svg3016.png")
![Mechanism for ADP-ribosylation, with residues of the catalyzing enzyme shown in blue.](/Images/godic/202412/20/ADP-Ribosylation-Mechanism3016.png")
![Crystal structure of PARP1 zinc finger domain bound to DNA (purple). PDB: 4AV1](/Images/godic/202412/20/PARP1_with_DNA3016.png")
![DNA repair facilitated by PARP1 recruitment of repair enzymes. Repair of a single strand break in DNA is initiated by the binding of PARP1. PARP1 binds single-strand breaks and pulls base excision repair intermediates close, leading to the synthesis of poly-ADP ribose. XRCC1 is the X-ray repair cross complementing protein 1. XRCC1 complexes with polynucleotide kinase (PNK) which processes DNA termini. PCNA is the proliferating cell nuclear antigen that serves as a DNA clamp that aids in the DNA polymerase activity (DNA pol) FEN1 (Flap endonuclease 1) is then recruited to remove the overhanging 5' flap. The last step of DNA repair involves DNA ligase which brings the final DNA strands together in a phosphodiester bond.](/Images/godic/202412/20/page1-220px-WikiDiagram1.pdf3017.jpg")
ADP-ribosylation is the addition of one or more ADP-ribose moieties to a protein. It is a reversible post-translational modification that is involved in many cellular processes, including cell signaling, DNA repair, gene regulation and apoptosis. Improper ADP-ribosylation has been implicated in some forms of cancer. It is also the basis for the toxicity of bacterial compounds such as cholera toxin, diphtheria toxin, and others.