Glycogen phosphorylase is a:

Glycogen phosphorylase is a phosphotransferase. It transfers one phosphoryl group to the non-reducing end of glycogen and releases glucose-1-phophate. This is known as phosphorolysis. Hydrolysis Phosphorolysis Breaking of covalent bonds using water R-O-R' + HOH - R-OH + R'-OH Breaking covalent bonds using ohophosphate. R-O-R' + HO-PO32- - R-OH + R'-O-PO32 e.g. Amylase and all protease enzymes. All hydrolase enzymes belong to EC3. e.g. Glycogen Phosphorylase; belongs to EC2 (transferase) Advantage of phosphorolysis over hydrolysis: Glucose produced is already in phosphorylated form. So, 1 ATP is gained/conserved if it enters glycolysis. Glucose-6-phosphate can't diffuse across the cell membrane freely. So,Glucose-6-phosphate in muscle can directly enter glycolysis as glucose-6-phosphatase is absent in myocyte.