Molecule of the Month: Insulin Receptor
The cellular receptor for insulin helps control the utilization of glucose by cells
When Things Go Wrong
Exploring the Structure
Insulin Receptor Tyrosine Kinase (PDB entries 1irk and 1ir3)
The tyrosine kinase portion of the receptor is itself a dynamic protein with many moving parts. The active site binds to ATP and uses it to phosphorylate its targets. In the inactive state (shown on the left, PDB entry 1irk ), a mobile loop (in bright turquoise) binds in the active site, blocking its action. When the receptor is activated, several tyrosines (green) on this loop are phosphorylated, causing it to swing out of the active site, allowing ATP (magenta) to enter (shown on the right, PDB entry 1ir3 ). Other signaling proteins (a small peptide from one is shown in pink) then bind and are phosphorylated on their tyrosine amino acids. To explore these two structures in more detail, click on the image for an interactive JSmol.
Topics for Further Discussion
- You can use the Protein Feature View for insulin receptor at the RCSB PDB to determine which portion of the receptor is included in each PDB entry.
- Several of the structures of the insulin-binding portion of the molecule, including entry 3loh, were determined by attaching antibodies to the receptor and crystallizing the complex. When you visualize these structures, be sure to ignore the antibodies, since they are not involved with the biological function of the molecule.
- There are many excellent online resources to learn about diabetes, such as the page at the World Health Organization and Diapedia.
February 2015, David Goodselldoi:10.2210/rcsb_pdb/mom_2015_2