In eukaryotic cells, 3 types of DNA polymerases (pol), pol alpha, pol delta and pol epsilon function in accurate and efficient DNA replication. Pol delta is a heteromultimeric enzyme composed of a 125 kDa major catalytic subunit and three smaller accessory subunits. Pol delta requires a number of accessory molecules to exert its full activity. Proliferating cell nuclear antigen (PCNA) forms a doughnut-shaped trimer with a 35 Ä hole and works as the sliding clamp and replication factor C acts as the clamp loader to improve Pol delta processivity. Pol delta is also involved in nucleotide excision repair of DNA.Synonyms: DNA polymerase delta subunit 2, DNA polymerase delta subunit p50