Description: Two-chain polypeptide hormone is produced by the beta-cells of pancreatic islets. It contains 51 amino acids and the molecular weight is ~5800 Dalton. The alpha and beta-chains are joined by two interchain disulfide bonds. The alpha chain contains an intrachain disulfide bond. Insulin regulates the cellular uptake, utilization, and storage of glucose, amino acids, and fatty acids and inhibits the breakdown of glycogen, protein, and fat. Insulin decreases blood glucose concentration. It increases cell permeability to monosaccharides, amino acids and fatty acids and accelerates glycolysis, the pentose phosphate cycle, and glycogen synthesis in liver.