Desmosomes provide strong cell–cell adhesion which is crucial for the integrity of tissues such as the epidermis. However, nothing is known about the distribution and binding properties of desmosomal adhesion molecules on keratinocytes. Here we used atomic force microscopy (AFM) to simultaneously visualize the topography of living human keratinocytes and the distribution and binding properties of the desmosomal adhesion molecule desmoglein 3 (Dsg3). Using recombinant Dsg3 as sensor, binding events were detectable diffusely and in clusters on the cell surface and at areas of cell–cell contact. This was blocked by removing Ca^2 + and by addition of Dsg3-specific antibodies indicating homophilic Dsg3 binding. Binding forces of Dsg3 molecules were lower on the cell surface compared to areas of cell–cell contact. Our data for the first time directly demonstrate the occurrence of Dsg3 molecules outside of desmosomes and show that Dsg3 adhesive properties differ depending on their localization.

Using atomic force microscopy in the study of keratinocytes, this study directly demonstrates the occurrence of desmoglein 3 molecules outside of desmosomes and reveales that the adhesive properties of these molecules do differ depending on their localization.