GLUCOKINASE AS GLUCOSE SENSOR AND METABOLIC SIGNAL GENERATOR IN PANCREATIC BETA-CELLS AND HEPATOCYTES

This article reviews evidence for a pivotal role of glucokinase as glucose sensor of the pancreatic β-cells. Glucokinase explains the capacity, hexose specificity, affinities, sigmoidicity, and anomeric preference of pancreatic islet glycolysis, and because stimulation of glucose metabolism is a prerequisite of glucose stimulation of insulin release, glucokinase also explains many characteristics of this β-cell function. Glucokinase of the β-cell is induced or activated by glucose in contrast to liver glucokinase, which is regulated by insulin. Tissue-specific regulation corresponds with observations that liver and pancreatic β-cell glucokinase are stucturally distinct. Glucokinase could play a glucose-sensor role in hepatocytes as well, and certain forms of diabetes mellitus might be due to glucokinase deficiencies in pancreatic β-cells, hepatocytes, or both.