Exploring the Nature of Desmosomal Cadherin Associations in 3D
Figure 5
Electron tomography of desmosomes from freeze-substituted resin-embedded epidermis of newborn mouse (a). Cadherin densities can be seen spanning the extracellular space and individual intermediate filaments projecting towards the cell membrane in the cytoplasm. The inset provides a magnified view of the irregular nature of cadherin association creating the dense mid-line. (b) In the cow snout stratum spinosium, cadherin densities can be seen spanning the extracellular space but the density of cadherin molecules is appreciably much higher. The dense mid-line can be observed by viewing the slice at a glancing angle however, in some areas, the irregular nature of cadherin association is visible (arrows) and can be seen magnified in the inset. Membranes are highlighted by lines and the cadherins by arrows in both a and b. (c) Cryoelectron tomography of isolated desmosomes in the frozen unstained state. A slice from a tomogram showing a desmosome which has curled up at the edge to provide a direct view of cadherin organisation. The two bilayers are clearly visible and a midline composed of globular densities can be seen bisecting the extracellular space (inset). These globular densities (arrow) probably correspond to the groups of cadherin molecules seen previously in freeze-substituted samples. Reproduced with permission from, [23] the Biochemical Society (http://www.biochemsoctrans.org/). Scale bars 50 nm.
