Anti-Phosphorylase B/PHKB antibody [EPR9035(2)]

Supplementary info

This supplementary information is collated from multiple sources and compiled automatically.

Activity summary

Phosphorylase B also known as PHKB plays a significant mechanical role in glycogen metabolism. It exists as a catalytic subunit in the phosphorylase kinase complex essential for glycogen breakdown. This enzyme consists of two subunits phosphorylase a and b but phosphorylase B acts in an inactive state requiring conversion for activity. In humans PHKB has several isoforms and a mass around 125 kDa. This protein is mainly expressed in skeletal muscle and liver tissues highlighting its importance in energy regulation within these areas.

Biological function summary

PHKB facilitates the regulation of glycogenolysis by modulating phosphorylase kinase activity. As part of the larger phosphorylase kinase complex it activates when calcium ions bind allowing phosphorylase A to exert its function on glycogen phosphorylase. This activation results in the breakdown of glycogen into glucose-1-phosphate an important step in maintaining energy supply during muscle exertion and fasting. PHKB forms a multimeric complex with other subunits including alpha beta gamma and delta each contributing to its full enzymatic function.

Pathways

PHKB integrates within key metabolic pathways especially the glycogen metabolism and signaling pathways linked to energy homeostasis. It collaborates with phosphorylase A enzymes to convert glycogen stores to free glucose in response to hormonal and neuronal signals. This process involves interconnected protein interactions such as with the protein kinases PKA and calmodulin subunits to ensure precise regulation of glycogenolysis under variable physiological conditions.

Associated diseases and disorders

Alterations in PHKB expression or function can lead to metabolic conditions. Glycogen storage disease type IXb a disorder characterized by muscle weakness and growth delay stems from mutations in the PHKB gene. This condition affects the ability to mobilize glycogen stores effectively resulting in restricted energy availability. PHKB's interaction with phosphorylase kinase subunits is vital in understanding its pathology connecting genetic mutations to broader metabolic dysfunctions.