Protein Phosphatase 1, Regulatory Subunit 3B (PPP1R3B)

The protein phosphatase-1 (PP1) catalytic subunit (PPP1CA) is regulated by targeting subunits, such as PP1R3B. PP1R3B suppresses the rate at which PP1 dephosphorylates (i.e., inactivates) glycogen phosphorylase (PYGL and enhances the rate at which it activates glycogen synthase (GYS2). Northern blot analysis detected a 6.7-kb GL transcript that was highly expressed in skeletal muscle and heart, followed by liver. Low levels of GL were detected in placenta, lung, and kidney. In mouse and rat, Gl predominated in liver, but only low levels of Gl were detected in skeletal muscle and other tissues. Western blot analysis revealed a 33-kD GL protein that was expressed at similar levels in human liver and skeletal muscle.