This domain is found in eukaryotes, and is approximately 70 amino acids in length. The family is found in association with pfam04042. There is a single completely conserved residue F that may be functionally important. This domain is the N terminal domain of DNA polymerase epsilon subunit B. It forms a primarily alpha helical structure in which four helices are arranged in two hairpins with connecting loops containing beta strands which form a short parallel sheet. DNA polymerase epsilon is required in DNA replication for synthesis of the leading strand. This domain has close structural relation to AAA+ protein C terminal domains.