PECAM1

PECAM1 is a member of the immunoglobulin (Ig) superfamily that is expressed on the surface of circulating platelets, monocytes, neutrophils, and particular T-cell subsets.

PECAM1 is also a major constituent of the endothelial cell intercellular junction, where up to an estimated 1 million molecules are concentrated.

Because of this cellular expression pattern, PECAM1 is implicated in several functions, including transendothelial migration of leukocytes, angiogenesis, and integrin activation.

Ig superfamily members are known to mediate cell adhesion, as:
 NCAM1 (MIM.116930)
 ICAM1 (MIM.147840)
 VCAM1 (vascular cell adhesion molecule-1) (MIM.192225)

They also mediate antigen recognition:
 immunoglobulins (IGH, IGL, IGK)
 T-cell receptors (TCRA, TCRB, TCRD, TCRG)
 MHC molecules.

In addition, a subgroup comprising 30 members characterized by the presence of one or more immunoreceptor tyrosine-based inhibitory motifs (ITIMs) within their cytoplasmic domain has also been recognized. PECAM1, which has 6 ITIMs within its cytoplasmic domain, is a member of this subfamily;