Protein phosphatase 1 regulatory subunit 3A is a protein in humans that is encoded by PPP1R3A gene. Seems to act as a glycogen-targeting subunit for PP1. PP1 is essential for cell division, and participates in the regulation of glycogen metabolism, muscle contractility and protein synthesis. Plays an important role in glycogen synthesis but is not essential for insulin activation of glycogen synthase (By similarity).