These proteins are typically transmembrane receptors and are composed of three domains: an intracellular domain that interacts with the cytoskeleton, a transmembrane domain, and an extracellular domain that interacts either with other CAMs of the same kind (homophilic binding) or with other CAMs or the extracellular matrix (heterophilic binding).

Families of CAMs

Most of the CAMs belong to 4 protein families: Ig (immunoglobulin) superfamily (IgSF CAMs), the integrins, the cadherins, and the selectins.

IgSF CAMs

Immunoglobulin superfamily CAMs (IgSF CAMs) are either homophilic or heterophilic and bind integrins or different IgSF CAMs.
Here is a list of some molecules of this family:

• NCAMs Neural Cell Adhesion Molecules
• ICAM-1 Intercellular Cell Adhesion Molecule
• VCAM-1 Vascular Cell Adhesion Molecule
• PECAM-1 Platelet-endothelial Cell Adhesion Molecule
• L1
• CHL1
• MAG
• Nectins and nectin-like molecules

Integrins

see also main article on Integrins

The integrins are a family of heterophilic CAMs that bind IgSF CAMs or the extracellular matrix. They are heterodimers, consisting in two noncovalently-linked subunits, called alpha and beta. Twenty-four different alpha subunits that can link in many different combinations with the 9 different beta subunits are known; however not all combinations are observed.

Some sources (for example, MeSH) don't consider integrins to be cell adhesion molecules.

Cadherins

see also main article on Cadherins

The cadherins are a family of homophilic CAMs, Ca²⁺-dependent. The most important members of this family are E-cadherins (epithelial), P-cadherins (placental), and N-cadherins (neural).

Selectins

The selectins are a family of heterophilic CAMs that bind fucosylated carbohydrates, e.g., mucins. They are calcium-dependent. The three family members are E-selectin (endothelial), L-selectin (leukocyte), and P-selectin (platelet). The best-characterized ligand for the three selectins is P-selectin glycoprotein ligand-1 (PSGL-1), which is a mucin-type glycoprotein expressed on all white blood cells.

Neutrophils and eosinophils bind to E-selectin. One of the reported ligands for E-selectin is the sialylated Lewis X Ag (sLe(x)). Eosinophils, like neutrophils, use sialylated, protease-resistant structures to bind to E-selectin, although the eosinophil expresses much lower levels of these structures on its surface. Ligands for P-selectin on eosinophils and neutrophils are similar sialylated, protease-sensitive, endo-beta-galactosidase-resistant structures, different than those reported for E-selectin, suggesting disparate roles for P-selectin and E-selectin during recruitment during inflammatory responses.

Neurological Diseases Associated With CAMs

Mental retardation and other neurological disorders are attributable in part to disruption of normal cell adhesion

Functions

• Embryonic development
• Formation of Nervous System
• Holding of tissues together in adults
• Inflammation and wound healing
• Metastasis of tumors
• Transmission of signals into and out of the cell

Footnotes

See also

• Cell adhesion
• Transmembrane receptors
• Extracellular matrix
• Integrin
• Cadherin
• Soluble cell adhesion molecules
• Substratum adhesion molecule (SAM)

External links