Molecule of the Month: P-glycoprotein
P-glycoprotein pumps toxic molecules out of our cells
Blocking the Pump
Exploring the Structure
P-glycoprotein is composed of one long chain that folds into two similar halves. In these pictures, the first half of the protein is colored blue and the second half is colored green. A short segment of protein linking the two halves is not seen in this crystal structure, and is shown here with a dotted line in magenta. Notice how similar the two halves are, and how extensive the overlapping area is between the two halves. Researchers have proposed that a gene duplication occurred during the evolution of the protein to connect these two similar halves into one long protein.
Two separate structures of P-glycoprotein are shown here, PDB entries 3g60 on the left and 3g61 on the right, which were solved with two different drug molecules, shown here in red. Notice how they bind in slightly different locations in the large active site of the protein. You can click on the image above for an interactive jmol version.
Topics for Further Discussion
- Bacteria build many different types of pumps for ejecting toxic molecules. Can you find examples in the PDB? Do they use a similar scissor-like mechanism?
- Can you find other examples of possible gene duplications in the PDB?
March 2010, David Goodselldoi:10.2210/rcsb_pdb/mom_2010_3