Glükogén

Glükogén is a polysaccharide that serves as the primary form of glucose storage in animals, fungi, and certain other organisms. It is a branched glucose polymer, meaning it is composed of many glucose units linked together in a branching structure. This structure allows for rapid mobilization of glucose when energy is needed, as enzymes can access the glucose units from multiple points within the molecule.

The majority of glucan storage occurs in the liver and muscles. Liver glucan is crucial for maintaining blood glucose homeostasis. When blood glucose levels drop, such as during fasting, the liver breaks down glucan into glucose, which is then released into the bloodstream to be used by other tissues. Muscle glucan, on the other hand, is primarily used as an energy source for muscle contraction. It is not released into the bloodstream but rather fuels the muscle cells directly.

The synthesis and breakdown of glucan are tightly regulated by hormones, primarily insulin and glucagon. Insulin promotes glucan synthesis (glucogenesis) when glucose levels are high, while glucagon stimulates glucan breakdown (glycogenolysis) when glucose levels are low. This dynamic interplay ensures that the body has a readily available supply of energy while preventing excessive fluctuations in blood sugar. Disorders in glucan metabolism can lead to various glycogen storage diseases, which have diverse clinical manifestations depending on the specific enzyme deficiency.