inactive DEDDy 3'-5' exonuclease domain of eukaryotic DNA polymerase zeta, a family-B DNA polymerase
The 3'-5' exonuclease domain of eukaryotic DNA polymerase zeta. DNA polymerase zeta is a family-B DNA polymerase which is distantly related to DNA polymerase delta. It plays a major role in translesion replication and the production of either spontaneous or induced mutations. In addition, DNA polymerase zeta also appears to be involved in somatic hypermutability in B lymphocytes, an important element for the production of high affinity antibodies in response to an antigen. The catalytic subunit contains both polymerase and 3'-5' exonuclease domains, but only exhibits polymerase activity. The DnaQ-like 3'-5' exonuclease domain contains three sequence motifs termed ExoI, ExoII and ExoIII, without the four conserved acidic residues that are crucial for metal binding and catalysis.