Glükokiinaas

Glükokiinaas, also known as hexokinase in some 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 first step in glycolysis, the breakdown of glucose. Specifically, it phosphorylates glucose, converting it into glucose-6-phosphate. This reaction traps glucose within the cell and prepares it for further metabolic processing.

The activity of glükokiinaas is distinct from other hexokinase isoforms due to its lower affinity for glucose. This means that glükokiinaas is only significantly active when glucose concentrations are relatively high, such as after a meal. This property allows it to act as a glucose sensor, particularly in the pancreas, where its activity influences insulin secretion. In the liver, glükokiinaas helps to store excess glucose as glycogen when blood glucose levels are high and releases glucose from glycogen when levels are low.

Genetic mutations affecting glükokiinaas can lead to metabolic disorders. For instance, mutations that result in reduced glükokiinaas activity can cause a form of maturity-onset diabetes of the young (MODY), specifically MODY2. Conversely, mutations leading to increased activity can potentially contribute to hypoglycemia. The enzyme's dual role in glucose sensing and metabolism makes it a key target for understanding and treating various metabolic conditions.