Molecule of the Month: Nanobodies
Unusual antibodies from camels are useful in research and medicine
Exploring the Structure
Nanobodies and Antibodies (PDB entries 1mel, 1t6v, 1mlc)
Since nanobodies are so small, they typically interact with a smaller portion of their targets when compared to other antibodies. This turns out to be an advantage, as seen by comparing the structure of a nanobody bound to lysozyme (PDB entry 1mel ) and a typical antibody Fab bound to the same target (PDB entry 1mlc ). The nanobody has a finger-shaped loop that pokes into the active site of lysozyme, forming interactions that mimic the substrate. The typical antibody, however, has a large cup-shaped binding site that can't fit into the active site, so it grips one side of the protein instead. Click on the image to explore these two structures along with the structure of a shark nanobody.
Topics for Further Discussion
- You can use the "Compare Structures" feature at the PDB to compare the structure of nanobodies with Fabs. To get started, try overlapping chain A of PDB entry 1mel with chain H of PDB entry 2ig2.
- Nanobodies have been useful tools for scientific research, and you can explore several of these structures in the PDB. For instance, PDB entry 3p0g includes a nanobody that was used to capture a cell receptor in an active conformation.
April 2011, David Goodselldoi:10.2210/rcsb_pdb/mom_2011_4