<p>This entry represents ribonuclease H1 (RNase H1; <db_xref db="EC" dbkey="3.1.26.4"/>) from eukaryotes. RNase H1 specifically degrades the RNA of RNA-DNA hybrids through endonucleolytic cleavage to 5'-phosphomonoester in the presence of magnesium. Human RNase H1 has a DNA-binding channel that, together with the conserved phosphate-binding pocket, confers specificity for the B form and 2'-deoxy form of DNA; the RNA strand is recognised by four consecutive 2'-OH groups and cleaved by a two-metal ion mechanism [<cite idref="PUB00042692"/>].</p>