Phosphorylation of serine and threonine residues in proteins is a crucial step in the regulation of many cellular functions ranging from hormonal regulation to cell division and even short-term memory. The level of phosphorylation is controlled by the opposing actions of protein kinases and protein phosphatases. Protein phosphatase 1 (PP1) is 1 of 4 major serine/threonine-specific protein phosphatases which have been identified in eukaryotic cells. PP1 associates with various regulatory subunits that dictate its subcellular localization and modulate its substrate specificity. Several subunits that target PP1 to glycogen have been identified. This gene encodes a glycogen-targeting subunit of PP1. [provided by RefSeq, Jul 2008].