Molecule of the Month: Cadherin
Adhesive cadherin proteins hold neighboring cells together
The tail of the cadherin chain crosses the cell membrane (shown schematically in gray) and is linked to the cytoskeleton by catenin proteins. Beta-catenin (shown here in blue from PDB entry 1i7x ) binds to the small tail of cadherin that hangs inside the cell. Alpha-catenin (not shown) then binds to beta-catenin and actin filaments.
Gluing Cells Together
Exploring the Structure
Cadherin Interaction (PDB entry 1lw3)
The adhesive contact between two cadherin proteins is formed when a tryptophan on one protein extends over and binds in a pocket on the other protein. The contact is shown here from PDB entry 1l3w . Notice the three calcium ions (in green) between the domains, which rigidify the whole structure. If you want to explore this interaction yourself, PDB entry 1l3w is a tricky structure to use, since you have to perform a crystallographic transformation to get the second protein structure (the transformation is a 180 degree rotation around the Y axis, which may be obtained with coordinates -x, y, -z). You can easily see the interaction, though, by looking at PDB entry 1nci , which only includes the last domain in each cadherin chain, but has two proteins in the PDB file. To explore this structure in more detail, click on the image for an interactive JSmol.
March 2008, David Goodselldoi:10.2210/rcsb_pdb/mom_2008_3