Accessory component of the DNA polymerase delta complex and possibly the DNA polymerase zeta complex (By similarity). As a component of the delta complex, participates in high fidelity genome replication, including lagging strand synthesis, DNA recombination and repair (PubMed:22532806, PubMed:25826374, PubMed:31100062). Required to recruit the DNA polymerase delta complex to the nucleus of rapidly dividing embryonic cells, and as a consequence is essential for genome replication during the earliest cell cycles (PubMed:31100062, PubMed:25826374). Increases the efficiency and processivity of DNA synthesis of the DNA polymerases during mitotic DNA replication and repair (PubMed:22532806, PubMed:25826374, PubMed:31100062). During development this function is essential for preventing replication stress that results in the formation of chromosomal fragile sites (CFS) such as chromosomal breaks (PubMed:31100062, PubMed:25826374). Ensures genomic stability by promoting several types of DNA repair mechanisms including repairing broken dicentric chromosomes through homolog-dependent break-induced replication (BIR) (PubMed:22532806, PubMed:25826374, PubMed:31053594). During homologous recombination (HR) repair, required for maintaining the processivity of the delta complex during break-induced replication; a form of HR that requires extensive DNA synthesis such as the repair of large gaps (PubMed:25826374, PubMed:22532806). Able to suppress position effect variegation and may therefore have a role in the induction of chromatin state changes that likely include its activities in DNA replication and repair (PubMed:25826374). Component of both the DNA polymerase delta and DNA polymerase zeta complexes (By similarity). The DNA polymerase delta complex consists 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 PolD1 and PolD2 (PubMed:31100062). Component of the DNA polymerase zeta complex consisting of four subunits: the catalytic subunit PolZ1 and three accessory subunits PolZ2/Rev7, PolD2/Pol31 and PolD3/Pol32 (By similarity). During oogenesis, detected in the nuclei of nurse cells, follicle cells, and in the nucleoplasm of the oocyte. In syncytial cell cycles, 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 ovaries (PubMed:25826374). Expressed in adult females and embryos (at the protein level). Oocytes and embryos lacking maternal PolD3, show no nuclear localization of the delta complex members PolD1 and PolD2, resulting in limited genome replication during the earliest cell cycles and thus early developmental arrest (PubMed:31100062). Mutants, presumably with maternal but not zygotic PolD3, develop normally however adults display a variable degree of bristle loss or shortening, and females are sterile while males are fertile (PubMed:31100062). In larval salivary glands, the delta complex localizes normally to the nuclei and chromosomes display a significant decrease in homologous recombination repair (PubMed:31100062). Chromosomes also exhibit spontaneous double strand breaks that primarily result from defects in genomic replication and, to a lesser extent, in DNA repair synthesis (PubMed:31100062).