Glucokinase enzyme (GK)

Glucokinase is a monomeric cytoplasmic enzyme primarily found in the liver and pancreatic β-cells, where it catalyzes the phosphorylation of glucose to glucose‐6‐phosphate—the first step in glycolysis. Unlike other hexokinases, glucokinase has a lower affinity for glucose and is not inhibited by its product at physiological concentrations, allowing it to function as an effective sensor for blood glucose levels within the physiologically relevant range. In hepatocytes, glucokinase facilitates glycogen synthesis during feeding states; in pancreatic β-cells, it acts as a key regulator linking blood sugar levels to insulin secretion. Structurally distinct from other hexokinases due to its monomeric form (~465 amino acids), glucokinase undergoes significant conformational changes upon substrate binding that are central to its regulatory properties. The enzyme’s activity is modulated allosterically—both directly by small molecule activators and indirectly via interaction with the glucokinase regulatory protein (GKRP) in liver cells. Genetic variants affecting glucokinase function can lead either to hyperglycemia or hypoglycemia syndromes; notably, loss-of-function mutations cause MODY2 diabetes while gain-of-function mutations may result in persistent hypoglycemic conditions. Pharmacologically targeting this enzyme with allosteric activators represents an emerging therapeutic strategy for type 2 diabetes but carries risks such as hypoglycemia if not carefully controlled due to enhanced hepatic or pancreatic activity.

Other names

Hexokinase IVHexokinase DGK

Allosteric activation by small molecules increases enzyme activity, enhancing hepatic glucose uptake and stimulating insulin secretion from pancreatic β-cells