As accessory component of the DNA polymerase epsilon (DNA polymerase II) participates in chromosomal DNA replication. It is required during synthesis of the leading and lagging DNA strands at the replication fork and binds at/or near replication origins and moves along DNA with the replication fork. It has 3'-5' proofreading exonuclease activity that correct errors arising during DNA replication. It is also involved in DNA synthesis during DNA repair (By similarity). The dpb3-dpb4 dimer associates with histone deacetylases, chromatin remodelers, and histones and plays a crucial role in the inheritance of histone hypoacetylation and H3K9 methylation in heterochromatin (PubMed:29109278). The dpb3-dpb4 dimer is also required for the recruitment of sir2 to heterochromatin (PubMed:29109278). DNA polymerase epsilon is a heterotetramer consisting of cdc20/Pol2, dpb2, dpb3, and dpb4 (By similarity). Forms also a heterodimer consisting dpb3 and dpb4 (PubMed:29109278). Interacts directly with cdc20/pol2 and dpb4 (PubMed:29109278). Displays partial loss of silencing in otr region as well as significant loss of silencing in mating-type and telomere (PubMed:29109278). Decreases H3K9 methylation more than 50%, whereas histone acetylation at the pericentromeric region is significantly increased (PubMed:29109278). Results in partial dissociation of swi6 from heterochromatin (PubMed:29109278). SPAC17G8.03c was previously identified as the homolog of budding yeast DBP3 in fission yeast. However, it was further demonstrated that SPCC16C4.22 is the true ortholog of DBP3.