Insulin is a 51-amino acid peptide hormone made up of 2 chains (A and B) connected by 2 disulfide bonds. There is an additional disulfide bond between 2 cysteine amino acids on Chain A.

Insulin plays a critical role in the human body. Made in the pancreas, this peptide hormone binds to receptors on cells, initiating a signal transduction cascade, which upregulates glucose transporter vesicles to the cell surface. Through this sequence of events, glucose is then taken into the cell and can be used by the cell for energy. Without this necessary protein, or if insulin resistance develops, diabetes may result. In our alpha carbon backbone 3-D model of insulin, Chain A (which has 21 amino acids) is purple and Chain B (which has 30 amino acids) is orange. The N-terminus and C-terminus of each chain is shown in blue and red, respectively. Cysteine sidechains that make disulfide bonds are shown in ball-and-stick format and CPK coloring scheme (Chain A: Cys6, Cys7, Cys11, Cys20. Chain B: Cys7, Cys19). The colors of the Insulin Model coordinate with the Insulin mRNA to Protein Kit©.

Frederick Banting and J.J.R. Macleod were awarded the 1923 Nobel Prize in Physiology or Medicine for the discovery of insulin.The primary structure of bovine insulin was first determined by Frederick Sanger in 1951. It was the first protein to have its sequence be determined. He was awarded the 1958 Nobel Prize in Chemistry for this work. For more information on insulin-related Nobel Prizes, visit and scroll down to Nobel Prizes and Nobel Prize Controversy.

This 5'' model is printed in plastic and should be handled with care. While much less fragile than plaster models, it can break if abused. Its PDB file is 2HIU.pdb.