Polymerase DNA Directed Delta 4 (POLd4)

The DNA polymerase delta complex is involved in DNA replication and repair, and it consists of the proliferating cell nuclear antigen (PCNA), the multisubunit replication factor C, and the 4 subunit polymerase complex: POLD1, POLD2, POLD3, and POLD4.The half-life of p12 was reduced approximately 30-fold after UV treatment, from 11 hours to 24 minutes, and p12 depletion was due to an accelerated rate of proteolysis that required proteasome activity and an active ubiquitin pathway. UV treatment converted the DNA polymerase delta complex in vivo to a 3-subunit enzyme lacking p12 that retained activity on poly(dA)/oligo(dT) templates but was impaired in its ability to extend singly primed M13 templates, suggesting that the loss of the p12 subunit compromised POLD activity.