Adhesion molecules

Proteins that occur on the cell membrane of almost all body cells and that establish a targeted contact between cells according to the receptor ligand principle, thus enabling communication (see below cell contacts or gap junctions). The cell-cell contact induces a variety of subsequent reactions, such as the formation of regulatory T cells (Treg), the intracellular activation of cytokines with consecutive events, remodelling and control of the cytoskeleton, cluster formation of surface proteins in the cell-cell contact area. Adhesion molecules (CAM) are preferably stored in vesicles within the cell and are only released into the environment of the cell through exocytosis by an external signal. This increases the concentration of adhesion molecules on the cell surface in a very short time. This leads to a temporary increase of the cell-cell contact, which also decreases again. The process of cell adhesion plays a role in the immune system, but also in tumor diseases.

Adhesion molecules (CAM) include:

• Integrins
• Selectines
• Cadherine
• Members of the superfamily of immunoglobulin genes: the immunoglobulin superfamily is so called because the individual members have structural similarities to immunoglobulins. They are expressed by the vascular endothelium and bind to integrins on the cell surface of leukocytes. These include:
• ICAM (Intercellular Cell Adhesion Molecule)
• VCAM (Vascular Cell Adhesion Molecule)
• PECAM (Platelet-Endothelial Cell Adhesion Molecule).

Adhesion molecules usually consist of an intracellular, a transmembrane and an extracellular domain. The actual adhesion is mediated by the extracellular domain. The intracellular domain is often used for signal transduction into the interior of the cell. Due to the important role that adhesion molecules play in leukocyte migration, they are interesting targets for novel therapies.