ICAMs

Adhesion receptors of the immuno-globulin superfamily are expressed in a wide variety of cell types, including cells of the nervous system, leukocytes and epithelial and endothelial cells.

This hetero-geneous expression pattern implicates Ig-CAMs in many diverse biological processes, such as brain development, immune responses, tissue sorting, epithelial morphogenesis and the development of the vascular network, to name but a few.

Ig-CAMs are characterized by the presence of one or more Ig-like domains in their extracellular region. In addition, the ectodomain of Ig-CAMs can contain various numbers of fibronectin type III (FNIII) repeats.

Although most Ig-CAMs have a transmembrane domain and a cytoplasmic tail, some of them are linked to the cell surface by a glycosylphosphatidylinositol anchor.

The best-characterized biological function of Ig-CAMs is the support of cell-cell adhesion through their homophilic interactions in trans.

Ig-CAMs can also exert heterophilic interactions, as different members of the Ig-CAM superfamily are known to bind to each other and even to other types of molecules, including components of the extracellular matrix.

Ig-CAMs associate with various proteins on the membrane of the same cell, such as growth-factor receptors, integrins and cadherins.

In addition, Ig-CAMs have several intracellular binding partners, ranging from effectors of signal-transduction pathways to cytoskeletal proteins. Ig-CAMs have a broad spectrum of biological functions of including cell adhesion, migration, signal transduction and the regulation of gene expression.

Members

The immunoglobulin family molecules include two endothelial adhesion molecules: ICAM1 (intercellular adhesion molecule-1) and VCAM1 (vascular cell adhesion molecule-1). Both these molecules serve as ligands for integrins found on leukocytes.

 ICAM1 (MIM.147840) - variations in susceptibility to malaria
 ICAM2 (MIM.146630)
 ICAM3 (MIM.146631)
 ICAM4
 ICAM5 (MIM.601852)

Pathology

 ICAM1 (MIM.147840) - variations in susceptibility to malaria

References

 Cavallaro U, Christofori G. Cell adhesion and signalling by cadherins and Ig-CAMs in cancer. Nat Rev Cancer. 2004 Feb;4(2):118-32. PMID: 14964308