– Protein Phosphatase 1 Regulatory Subunit 1A (PPP1R1A) is an inhibitor of protein-phosphatase 1. PPP1R1A is a cellular regulator of eIF2 alpha phosphorylation. In hormonal control of glycogen metabolism, IPP-1 protein plays important function. Hormones can elevate intracellular cAMP level and elevate IPP-1 activity. PPP1R1A activation caused cAMP increase , cAMP control over proteins that are not directly phosphorylated by PKA following a rise in intracellular calcium. IPP-1 is inactivated by calcineurin (PP2B). Multiple domains in IPP-1 target cellular PP1 complexes.