Glycogen storage disease type I as fat. When digestion of a meal is complete, insulin levels fall, and enzyme systems in the liver cells begin to remove glucose molecules from strands of glycogen in the form of G6P. This process is termed glycogenolysis. The G6P remains within the liver cell unless the phosphate is cleaved by glucose-6-phosphatase. This dephosphorylation reaction produces free glucose and free anions. The free glucose molecules can be transported out of the liver cells into the blood to maintain an adequate supply of glucose to the brain and other organs of the body. Glycogenolysis can supply the glucose needs of an
Glucose 6-phosphate body needs a way to store the excess glucose. After being converted to G6P, the molecule can be turned into glucose-1-phosphate by phosphoglucomutase. Glucose-1-phosphate can then be combined with uridine triphosphate (UTP) to form UDP-glucose, driven by the hydrolysis of UTP, releasing phosphate. Now, the activated UDP-glucose can add to a growing glycogen molecule with the help of glycogen synthase. This is a very efficient storage mechanism for glucose since it costs the body only 1 ATP to store the 1 glucose molecule and virtually no energy to remove it from storage. It is important to note that glucose-6-phosphate is