Glycogen Phosphorylase BB/GPBB Proteins and Enzymes

Glycogen phosphorylase is a dimeric enzyme that catalyzes the first step in the breakdown of glycogen to release glucose in hypoglycemic or hypoxic conditions. The enzyme exists as a homodimer of liver (L), muscle (M), or brain (B) subunits. The BB isozyme is the predominant form in the myocardium, and its soluble form serves as a sensitive marker of myocardial infarction and other types of ischemic myocardial damage.