As the accessory component of the DNA polymerase zeta complex, involved in translesion DNA synthesis (TLS) and various DNA repair mechanisms (PubMed:15175013, PubMed:16507570). Promotes the apurinic/apyrimidinic (AP) endonuclease activity of Rrp1 and is therefore likely to be involved in the base excision repair (BER) pathway responsible for repair of DNA lesions (PubMed:16507570). It does not appear to influence the synthesis activity of the catalytic component Dmpol-zeta (PubMed:15175013). Accessory subunit of the zeta DNA polymerase complex, which consists of the catalytic component PolZ1/DNApol-zeta and PolZ2/Rev7 (PubMed:16507570, PubMed:15175013). Interacts with the apurinic/apyrimidinic (AP) endonuclease Rrp1 (via the N-terminus) (PubMed:16507570). Expressed throughout development, with slightly higher levels of expression in 0-4 hour embryos, larvae and adults. Belongs to the MAD2 family. Extended N-terminus.