This family contains a number of DNA polymerase subunits. The B subunit of the DNA polymerase alpha plays an essential role at the initial stage of DNA replication in S. cerevisiae and is phosphorylated in a cell cycle-dependent manner. DNA polymerase epsilon is essential for cell viability and chromosomal DNA replication in budding yeast. In addition, DNA polymerase epsilon may be involved in DNA repair and cell-cycle checkpoint control. The enzyme consists of at least four subunits in mammalian cells as well as in yeast. The largest subunit of DNA polymerase epsilon is responsible for polymerase epsilon is responsible for polymerase activity. In mouse, the DNA polymerase epsilon subunit B is the second largest subunit of the DNA polymerase. A part of the N-terminal was found to be responsible for the interaction with SAP18. Experimental evidence suggests that this subunit may recruit histone deacetylase to the replication fork to modify the chromatin structure.