Repair of genomic uracil post-replication through short-patch BER. UNG2 is the primary DNA glycosylase associated with replication, while SMUG1, TDG, and MBD4 are backups or have specific substrate specificity. UNG2 removes uracil, generating an AP site intermediate, which is subsequently incised by APE1 forming a ssDNA break. Although PARP can sense and be recruited to ssDNA breaks, the scaffold protein XRCC1’s recruitment and the action of DNA polymerase (Pol) are essential to further process the ssDNA break and insert the correct nucleotide. Short-patch BER is completed through ligation by DNA ligase III, while long-patch BER involves ligase I.11,12
