glükokiinasis

Glükokiinaas, also known as hexokinase in other contexts, is an enzyme that plays a crucial role in cellular metabolism. It is primarily found in the liver and pancreatic beta cells of mammals. The main function of glükokiinaas is to catalyze the phosphorylation of glucose, converting it into glucose-6-phosphate. This initial step is essential for glucose metabolism, trapping glucose within the cell and preparing it for further breakdown through glycolysis or storage as glycogen.

The activity of glükokiinaas is distinct from other hexokinases in that it has a lower affinity for glucose and is not inhibited by its product, glucose-6-phosphate. This characteristic allows it to function as a glucose sensor, particularly in the liver and pancreas. In the liver, glükokiinaas helps regulate blood glucose levels by taking up glucose when blood sugar is high and initiating its storage. In pancreatic beta cells, glükokiinaas acts as the primary sensor for glucose-induced insulin secretion. When glucose enters beta cells, glükokiinaas phosphorylates it, leading to increased ATP production. This change in ATP/ADP ratio triggers the closure of ATP-sensitive potassium channels, depolarization of the cell membrane, influx of calcium, and ultimately, the release of insulin. Mutations in the gene encoding glükokiinaas can lead to diabetes mellitus, either by causing a deficiency in insulin secretion or by altering glucose sensing mechanisms.