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.May play an important role in dephosphorylating substrates such as the postsynaptic density-associated Ca2+/calmodulin dependent protein kinase II.Component of the PTW/PP1 phosphatase complex,which plays a role in the control of chromatin structure and cell cycle progression during the transition from mitosis into interphase.