Two non-identical subunits, one large subunit and four minor subunits, make up the C-terminal of the large subunit of exonuclease VII (IPR020579). A substance called exonuclease VII cuts exons in two directions, either 5'-3' or 3'-5'. This creates 5'-phosphate mononucleotides. An OB-fold domain is also present in the large subunit, which is responsible for binding to the N-terminal nuclease.