Molecule of the Month: Insulin
The hormone insulin helps control the level of glucose in the blood
A Molecular Messenger
Folding Tiny Proteins
Exploring the Structure
Insulin (PDB entry 1trz)
Insulin is a perfect molecule for exploring protein structure. It is small enough that you can display all of the atoms and still have a picture that is not too confusing. Human insulin is pictured here, using entry 1trz. This structure, like many other insulin structures, includes a hexameric complex of the hormone, and only one monomer (composed of one A-chain and one B-chain) is shown here. In the structure, you can see many of the key features that stabilize protein structure. Carbon-rich amino acids, like leucine and isoleucine, cluster in the middle of the molecule, forming a hydrophobic core, and the surface is covered with charged amino acids like arginine and glutamate that interact favorably with the surrounding water. Also notice the three disulfide bridges between cysteine amino acids, which stabilize this tiny protein. To explore these features in more detail, click on the image for an interactive JSmol.
Topics for Further Discussion
- A paper model is available on PDB-101 to explore the folding of the two insulin chains, including a template for the model and an activity page.
- The hexameric complex of insulin is used to store the hormone before release. For more information, look at the Molecule of the Month on Designer Insulins.
February 2001, David Goodselldoi:10.2210/rcsb_pdb/mom_2001_2