Cell Adhesion Molecules (CAMs) are proteins located on the cell surface involved with the binding with other cells or with the extracellular matrix (ECM) in the process called cell adhesion.
These proteins are tipically 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
- ICAMs Intercellular Adhesion Molecules
- VCAM-1 Vascular Cell Adhesion Molecule
- PECAM-1 Platelet-endothelial Cell Adhesion Molecule
- L1
- CHL1
Selectins
The selectins are a family of heterophilic CAMs that bind fucosylated carbohydrates, e.g. mucins . They are dependent on divalent cations. The most important family members are E-selectins (endothelial), L-selectins (leukocyte) and P-selectins (platelet). An example of a member of this family is the P-selectin glycoprotein ligand-1 (PSGL-1 ).
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 non-covalently linked subunits, called alpha and beta. 15 different alpha subunits are known that can link in many different combinations with the 8 different beta subunits, however not all combinations are observed.
Cadherins
- see also main article on Cadherins
The cadherins are a family of homophilic CAMs, Calcium dependant. The most important members of this family are E-cadherins (epithelial), P-cadherins (placental) and N-cadherins (neural).
See also