<Dd> glycogen + P ⇌ glycogen + glucose - 1 - phosphate </Dd> <P> Here, glycogen phosphorylase cleaves the bond linking a terminal glucose residue to a glycogen branch by substitution of a phosphoryl group for the α (1 → 4) linkage . Glucose - 1 - phosphate is converted to glucose - 6 - phosphate by the enzyme phosphoglucomutase . Glucose residues are phosphorolysed from branches of glycogen until four residues before a glucose that is branched with a α (1 → 6) linkage . Glycogen debranching enzyme then transfers three of the remaining four glucose units to the end of another glycogen branch . This exposes the α (1 → 6) branching point, which is hydrolysed by α (1 → 6) glucosidase, removing the final glucose residue of the branch as a molecule of glucose and eliminating the branch . This is the only case in which a glycogen metabolite is not glucose - 1 - phosphate . The glucose is subsequently phosphorylated to glucose - 6 - phosphate by hexokinase . </P> <P> Glycogenolysis takes place in the cells of the muscle and liver tissues in response to hormonal and neural signals . In particular, glycogenolysis plays an important role in the fight - or - flight response and the regulation of glucose levels in the blood . </P> <P> In myocytes (muscle cells), glycogen degradation serves to provide an immediate source of glucose - 6 - phosphate for glycolysis, to provide energy for muscle contraction . </P>

Where does glycogenolysis take place in the cell