In DNA replication, exonucleases are involved in the processing of Okazaki fragments, whereas in DNA repair, they function to excise damaged DNA fragments and correct recombinational mismatches. These exonucleases include the family of DNA polymerases, namely DNA pol alpha, beta, delta and epsilon. DNA pol delta and DNA pol epsilon are multisubunit enzymes, with DNA pol delta consisting of two subunits which interact with the sliding DNA clamp protein PCNA.