Cell adhesion

Cell adhesion is the process cells interact and attach to a surface, substrate or another cell, mediated by interactions between molecules of the cell surface. Cell adhesion occurs from the action of transmembrane glycoproteins, called cell adhesion molecules. Examples of these proteins include selectins, integrins, syndecans, and cadherins. Cellular adhesion is essential in maintaining multicellular structure. Cellular adhesion can link cells in different ways and can be involved in signal transduction. Cell adhesion is also essential for the pathogenesis of infectious organisms.

Protozoans express multiple adhesion molecules. An example of a pathogenic protozoan is the malarial parasite (Plasmodium falciparum), which uses one adhesion molecule called the circumsporozoite protein to bind to liver cells, and another adhesion molecule called the merozoite surface protein to bind red blood cells.

Mammalian cells express many different types of adhesion molecules. The major classes are named integrins, Ig superfamily members, cadherins, and selectins. Each of these adhesion molecules has a different function and recognizes different ligands. Defects in cell adhesion are usually attributable to defects in expression of adhesion molecules.

Cell junctions allow cells to adhere to one another in multicellular organisms. There are 4 types of cell junctions:

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