Exonuclease V is a monomeric 5' deoxyribonuclease that is localized in the nucleus. It degrades single-stranded, but not double-stranded, DNA from the 5'-end, and the products are dinucleotides, except the 3'-terminal tri- and tetranucleotides, which are not degraded. The initial hydrolytic cut of exonuclease V on the dephosphorylated substrate produces a mixture of dinucleoside monophosphates and trinucleoside diphosphates. The enzyme is processive in action. Exo5 is specific for single-stranded DNA and does not hydrolyze RNA. However, Exo5 has the capacity to slide across 5' double-stranded DNA or 5' RNA sequences and resume cutting two nucleotides downstream of the double-stranded-to-single-stranded junction or RNA-to-DNA junction, respectively.