CD31 is a single chain integral membrane glycoprotein member of the immunoglobulin superfamily of cell adhesion molecules with molecular mass of 130-140kDa. It has six Ig-like loops in the extracellular domain, a trans-membrane domain including a relatively long cytoplasmic domain. It is expressed abundantly on platelets, myeloid cells, B lymphocytes, certain T-lymphocyte cell subsets, bone marrow precursor cells, NK cells and localized to the intracellular junctions in monolayers of cultured endothelial cells.
CD31 is also known as PECAM-1 (Platelet endothelial cell adhesion molecule-1) binds to glycosaminoglycans (GAG). Endothelial CD31 is phosphorylated on tyrosine and serine residues. CD31 is involved in some of the interactive events taking place during cardiovascular development inflammation, thrombosis, wound healing and angiogenesis.