Both prokaryotic and eukaryotic H2 enzymes can cleave single ribonucleotides in a strand. however, they have slightly different cleavage patterns and substrate preferences: prokaryotic enzymes have lower processivity and hydrolyze successive ribonucleotides more efficiently than ribonucleotides with a 5' deoxyribonucleotide, while eukaryotic enzymes are more processive and hydrolyze both types of substrate with similar efficiency. The substrate specificity of RNase H2 gives it a role in ribonucleotide excision repair, removing misincorporated ribonucleotides from DNA, in addition to R-loop processing. Although both H1 and H2 are present in the mammalian cell nucleus, H2 is the dominant source of RNase H activity there and is important for maintaining genome stability.