Glycogen store roughly 100–120 grams of glycogen. In skeletal muscle, glycogen is found in a low concentration (1–2% of the muscle mass) and the skeletal muscle of an adult weighing 70 kg stores roughly 400 grams of glycogen. The amount of glycogen stored in the body—particularly within the muscles and liver—mostly depends on physical training, basal metabolic rate, and eating habits. Small amounts of glycogen are also found in other tissues and cells, including the kidneys, red blood cells, white blood cells, and glial cells in the brain. The uterus also stores glycogen during pregnancy to nourish the embryo. Approximately 4
Glucose 6-phosphate an allosteric activator of glycogen synthase, which makes sense because when the level of glucose is high the body should store the excess glucose as glycogen. On the other hand, glycogen synthase is inhibited when it is phosphorylated by protein kinase during times of high stress or low levels of blood glucose, via hormone induction by glucagon or adrenaline. When the body needs glucose for energy, glycogen phosphorylase, with the help of an orthophosphate, can cleave away a molecule from the glycogen chain. The cleaved molecule is in the form of glucose-1-phosphate, which can be converted into G6P by phosphoglucomutase.