Fig. 4. Schematic representation of the Dsc2 ectodomain model 3D array, generated from the crystallographic structure of C-cadherin (Boggon et al., 2002). In the centre the desmosomal interspace is represented as a cylinder, showing the mid-line formed by trans and cis interactions between molecules on opposed cell surfaces. Monomers from one cell surface are coloured in red and monomers from the opposed cell surface are coloured in blue. The midline is aligned with the x-axis of the cylinder (coincident with the x-axis in the crystallographic lattice). Rotation of the 3D array around the x-axis by 90° (top) shows a regular lattice with distances between rows of molecules of 73.85 Å and distances of 75.14 Å between layers. Rotations around the z-axis produce four different views, all of them with a midline dense zone (bottom). These are: strand dimer 1 at z=0°; `boat' at z=30°, strand dimer 2 (inverse form of strand dimer 1) at z=60° and `zipper' at z=120°. The cis and trans interfaces between distal domains are indicated by arrows.