Glucokinase/GCK Protein, Human

The Glucokinase (GCK) protein is a pivotal player in glucose metabolism, catalyzing the phosphorylation of hexoses such as D-glucose, D-fructose, and D-mannose, to form hexose 6-phosphate—specifically, D-glucose 6-phosphate, D-fructose 6-phosphate, and D-mannose 6-phosphate. Notably, GCK exhibits a weaker affinity for D-glucose compared to other hexokinases and is most effective when glucose is abundant. Its predominant expression in pancreatic beta cells and the liver positions GCK as a rate-limiting step in glucose metabolism within these tissues. Acting as a glucose sensor in pancreatic beta cells, GCK's low glucose affinity allows it to modulate insulin secretion in coordination with glucose concentrations. In the liver, GCK plays a crucial role in facilitating glucose uptake and conversion, acting as an insulin-sensitive determinant of hepatic glucose usage. Additionally, GCK is essential for providing D-glucose 6-phosphate in the synthesis of glycogen and mediates the initial step of glycolysis by catalyzing the phosphorylation of D-glucose to D-glucose 6-phosphate.