Glycogen storage disease type I similar, but Ib incurs a few additional problems (described below). Glycogen in liver and (to a lesser degree) kidneys serves as a form of stored, rapidly accessible glucose, so that the blood glucose level can be maintained between meals. For about 3 hours after a carbohydrate-containing meal, high insulin levels direct liver cells to take glucose from the blood, to convert it to glucose-6-phosphate (G6P) with the enzyme glucokinase, and to add the G6P molecules to the ends of chains of glycogen (glycogen synthesis). Excess G6P is also shunted into production of triglycerides and exported for storage in adipose tissue
Glucose 6-phosphatase variety of muscles across the animal kingdom, albeit at very low concentrations. Thus, the glycogen that muscles store is not usually available for the rest of the body's cells because glucose-6-phosphate cannot cross the sarcolemma unless it is dephosphorylated. The enzyme plays an important role during periods of fasting and when glucose levels are low. It has been shown that starvation and diabetes induces a 2-3-fold increase in glucose-6-phosphatase activity in the liver. Glc 6-Pase activity also increases dramatically at birth when an organism becomes independent of the mothers source of glucose. The human Glc 6-Pase gene contains five exons