NER unfolds in three distinct stages: recognition, verification and repair ... to fill in the gap left behind. Finally, the DNA backbone is sealed, and the damaged DNA is restored back to health.

Apurinic/apyrmidinic endonuclease 1 (APE1) plays a central role in DNA repair by cleaving the DNA backbone 5′ of AP ... the steps in BER may involve recognition of a product–enzyme complex ...

Bacteria protect their DNA by modifying their own recognition sequences ... with complementary sticky ends are joined, the DNA backbone may be covalently sealed using another enzyme called ...