In addition, two other types of anchoring junctions can be found where epithelial cells rest on the connective tissue matrix. These focal adhesions (focal contacts) and hemidesmosomes are discussed in the section on the basal domain (see pages 144 to 146).
Cell adhesion molecules play important roles in cell-tocell and cell-to–extracellular matrix adhesions.
Transmembrane proteins known as cell adhesion mole cules (CAMs) form an essential part of every anchoring junction on both lateral and basal cell surfaces. The extracellular domains of CAMs interact with similar domains belonging to CAMs of neighboring cells. If the binding occurs between different types of CAMs it is described as heterotypic binding; homotypic binding occurs between CAMs of the same type (Fig. 5.18). CAMs have a selective adhesiveness of relatively low strength, which allows cells to easily join and dissociate.
 FOLDER 5.3 Clinical Correlation: Junctional Complexes as a Target of Pathogenic Agents