Protein phosphatase that associates with over 200 regulatory proteins to form highly specific holoenzymes which dephosphorylate hundreds of biological targets.Protein phosphatase 1(PP1)is essential for cell division,and participates in the regulation of glycogen metabolism,muscle contractility and protein synthesis.Dephosphorylates RPS6KB1.Involved in regulation of ionic conductances and long-term synaptic plasticity.