Cadherin mechanics and complexation: the importance of calcium binding

Biophys J. 2005 Dec;89(6):3895-903. doi: 10.1529/biophysj.105.067322. Epub 2005 Sep 23.


E-cadherins belong to a family of membrane-bound, cellular adhesion proteins. Their adhesive properties mainly involve the two N-terminal extracellular domains (EC1 and EC2). The junctions between these domains are characterized by calcium ion binding sites, and calcium ions are essential for the correct functioning of E-cadherins. Calcium is believed to rigidify the extracellular portion of the protein, which, when complexed, adopts a rod-like conformation. Here, we use molecular dynamics simulations to investigate the dynamics of the EC1-2 portion of E-cadherin in the presence and in the absence of calcium ions. These simulations confirm that apo-cadherin shows much higher conformational flexibility on a nanosecond timescale than the calcium-bound form. It is also shown that although the apo-cadherin fragment can spontaneously complex potassium, these monovalent ions are incapable of rigidifying the interdomain junctions. In contrast, removal of the most solvent-exposed calcium ion at the EC1-2 junction does not significantly perturb the dynamical behavior of the fragment. We have also extended this study to the cis-dimer formed from two EC1-2 fragments, potentially involved in cellular adhesion. Here again, it is shown that the presence of calcium is an important factor in both rigidifying and stabilizing the complex.

MeSH terms

  • Binding Sites
  • Cadherins / chemistry*
  • Calcium / chemistry*
  • Computer Simulation
  • Kinetics
  • Mechanics
  • Models, Chemical*
  • Models, Molecular*
  • Molecular Conformation
  • Motion
  • Protein Binding
  • Protein Structure, Tertiary


  • Cadherins
  • Calcium