PYGL (E4O1P) Rabbit mAb #42103

Glycogen phosphorylases constitute a family of metabolic enzymes that catalyze the rate-limiting step in the release of glucose-1-phosphate (G1P) from tissue glycogen stores (1,2). There are three distinct glycogen phosphorylases in vertebrates, encoded by distinct genes and characterized primarily by the tissues in which they are predominantly expressed: PYGL (liver form), PYGB (brain form), and PYGM (muscle form). All three forms are expressed as inactive monomers, which require homodimerization and site-specific phosphorylation for activation, with additional regulation possible via other post-translational modifications such as O-GlycNAcylation (3). Due to their critical role in regulating glycogen catabolism, mutations or other perturbations that impact glycogen phosphorylase activity have been identified as contributing factors to metabolic diseases (e.g., glycogen storage diseases) and other diseases with metabolic dependencies, including cancer (4,5). While PYGL is expressed predominantly in the liver, it is understood to regulate systemic (blood) glucose levels via the catabolism of liver glycogen stores, whereas PYGB and PYGM regulate glycogen metabolism specifically within brain and skeletal muscle tissues, respectively (6,7).