As the catalytic component of the DNA polymerase delta complex, plays a crucial role in high fidelity genome replication, including lagging strand synthesis, DNA recombination and repair (By similarity). Exhibits both DNA polymerase and 3'- to 5'-exonuclease activities (PubMed:7907087, PubMed:8415662, PubMed:1360647). Required at the nucleus of rapidly dividing embryonic cells to activate genome replication during the earliest cell cycles (PubMed:31100062). Likely to require the presence of accessory proteins PolD2 and PolD3 for full activity (PubMed:31100062). a 2'-deoxyribonucleoside 5'-triphosphate + DNA(n) = diphosphate + DNA(n+1) Binds 1 [4Fe-4S] cluster. Inhibited by KCL (PubMed:7907087, PubMed:1360647). Also inhibited by carbonyldiphosphonate, aphidicolin and N-ethylmaleimide (NEM) (PubMed:7907087, PubMed:8415662, PubMed:1360647). Optimum pH is 7.2. Catalytic component of the DNA polymerase delta complex consisting of three subunits: the catalytic subunit PolD1 and two accessory subunits PolD2/Pol31 and PolD3/Pol32 (PubMed:31100062). Within the delta complex, interacts with both PolD2 and PolD3, and is able to interact with PolD2 in the absence of PolD3 (PubMed:31100062). Interacts with PCNA AND PCNA2 (PubMed:17087725). In embryos, accumulates in the nucleus during interphase but disperses into the nucleoplasm at the onset of mitosis. Expressed in ovaries (at the protein level) (PubMed:31100062). Expressed in embryos (at the protein level) (PubMed:31100062, PubMed:7907087, PubMed:8415662, PubMed:1360647). The CysB motif binds 1 4Fe-4S cluster and is required for the formation of polymerase complexes. In eukaryotes there are five DNA polymerases: alpha, beta, gamma, delta, and epsilon which are responsible for different reactions of DNA synthesis. Belongs to the DNA polymerase type-B family.