Desmosomes in a tangle

Intermediate filament–associated desmosomes—like their actin-associated counterparts, adherens junctions—link neighboring epithelial cells through cadherin connections. Crystal structure analyses of adherens junction cadherins suggested that these proteins interact at their NH₂-terminal tips. A recent model shows that the most distal of five extracellular domains, called EC1, contains a tryptophan that can nestle in a hydrophobic pocket of an opposing cadherin's EC1. Other studies suggested that strong adhesion could only be produced by more extensive interactions along the extracellular arms.

Using electron tomography—EM with tilting to give three-dimensional information—Wanzhong He, Pamela Cowin, and David Stokes (New York University, New York, NY) now get a better view of EC1 interactions and other cadherin contacts in desmosomes.

The tomographical maps revealed that the cadherins adopt geometries resembling the letters S, W, and λ. Based on...