Hexokinase (includes Hexokinase I, II, III) and Glucokinase (Hexokinase IV) (HK (for hexokinase family); GCK (for glucokinase))

Hexokinase refers to a family of enzymes (hexokinase I, II, III) that catalyze the first step in glucose metabolism by phosphorylating glucose to yield glucose-6-phosphate, a reaction fundamental to glycolysis and other metabolic pathways[1][3][5]. Hexokinases I-III are widely distributed, with high affinity for glucose, and are inhibited by their product, glucose-6-phosphate, providing feedback regulation[3][5]. Glucokinase (hexokinase IV, also known as GCK or hexokinase D) is an isozyme primarily found in the liver and pancreatic β-cells. It has a lower affinity but higher capacity for glucose, is not inhibited by glucose-6-phosphate, and acts as a glucose sensor in the pancreas to regulate insulin secretion and facilitate hepatic glucose uptake and storage[1][4][5][7]. While hexokinase II is important for energy homeostasis in muscle and is frequently upregulated in cancers, glucokinase’s function is crucial for glucose homeostasis, and genetic defects in glucokinase can lead to forms of diabetes or hypoglycemia[1][4][5]. Drugs targeting these enzymes aim to modulate glucose metabolism, with applications in diabetes, cancer, and metabolic disorders. However, excessive modulation can have risks, including hypoglycemia and potential promotion of tumorigenesis[1][5].

Other names

Hexokinase I, II, IIIHexokinase IVGlucokinaseHK1, HK2, HK3, HK4GCK (for glucokinase)Hexokinase D (for glucokinase)

Enzyme inhibition (e.g., 2-deoxyglucose inhibits glucose phosphorylation) - Enzyme activation (e.g., glucokinase activators increase glucose phosphorylation and insulin secretion) - Modulation of glycolytic flux, altering glucose utilization