Insulin is the one of the most important hormones in the human body. This hormone is synthesized in the pancreatic β-cells within the islets of Langerhans and controls glucose uptake from the blood by cells of various organs and tissues.

Insulin is a small protein composed of two polypeptide chains. The A-chain (indicated by the dark shading) consists of 21 amino acid residues, and the B-chain (lighter shading) consists of 30 residues. The chains are connected by two disulfide bonds (the attached spheres on the model). One additional disulfide bond is located inside the A-chain. This model illustrates the structure of porcine insulin [1], which differs from human insulin [2] by one amino acid residue in the 30th position of the B-chain. Insulin is stored in the body as a hexamer, whereas the functional form of this hormone is monomeric [3, 4].

Date: Dec 10, 2011


  1. Baker E.N. et al., Philos Trans R Soc Lond B Biol Sci. 1988 Jul 6;319(1195):369-456.
  2. Ciszak E. et al., Biochemistry. 1994 Feb 15;33(6):1512-7.
  3. Chang X. et al., Biochemistry. 1997 Aug 5;36(31):9409-22.
  4. Dunn MF., Biometals. 2005 Aug;18(4):295-303.