Phosphorylase b, derived from rabbit muscle, is primarily used in biochemical research to study glycogen metabolism. It plays a crucial role in understanding the regulation of glycogen breakdown, particularly in muscle tissues. Researchers utilize this enzyme to investigate the mechanisms of allosteric regulation and phosphorylation, which are key to controlling its activity. It is also employed in enzymatic assays to measure glycogen phosphorylase activity, aiding in the study of metabolic disorders and the development of therapeutic strategies. Additionally, it serves as a model enzyme in structural biology to explore protein-ligand interactions and enzyme kinetics.