Protein phosphatases are enzymes that dephosphorylate proteins; these include proteins with important roles in signal transduction pathways in both eukaryotic and bacterial cells. Protein phosphatases can be further subdivided into those that dephosphorylate Ser and Thr residues, the phosphoprotein (PPP) family, and the Mg2+/Mn2+-dependent protein phosphatase (PPM) family. In a Mg 2+ /Mn 2+ -dependent manner, serine/threonine phosphatase (PPM, IPR001932) dephosphorylates Ser and Thr residues. Protein phosphatase M (PPM) is a protein that dephosphorylates proteins that contain phosphoserine or phosphothreonine as their central structure. The catalytic domain of PPM1H phosphatase, like that of other PPM (PP2C) enzymes, is Mg 2+ /Mn 2+ dependent.