glukokináza

Glukokináza is an enzyme found primarily in the liver and pancreatic beta cells. It plays a crucial role in glucose metabolism by catalyzing the phosphorylation of glucose to glucose-6-phosphate. This reaction is the first committed step in glycolysis and glycogen synthesis.

Unlike other hexokinases, glukokináza has a relatively low affinity for glucose, meaning it functions most effectively at higher glucose concentrations. This characteristic allows it to act as a glucose sensor. In the liver, when blood glucose levels rise after a meal, glukokináza becomes active, promoting glucose uptake and storage as glycogen. Conversely, when blood glucose levels fall, glukokináza activity decreases, allowing the liver to release stored glucose.

In the pancreatic beta cells, glukokináza's low affinity for glucose is essential for regulating insulin secretion. As blood glucose levels increase, glukokináza phosphorylates glucose, leading to an increase in intracellular ATP. This ATP rise closes ATP-sensitive potassium channels, causing cell depolarization and the influx of calcium ions, which triggers insulin release. Mutations in the glukokináza gene can lead to diabetes mellitus, either due to impaired insulin secretion or altered hepatic glucose regulation. Glukokináza is also known as hexokinase IV or glucokinase.