PECAM-1 is a 130-120-kD integral membrane glycoprotein found on the surface of platelets, at endothelial intercellular junctions in culture, and on cells of myeloid lineage. Previous studies have shown that it is a member of the immunoglobulin gene superfamily and that antibodies against the bovine form of this protein (endoCAM) can inhibit endothelial cell-cell interactions. These data suggest that PECAM-1 may function as a vascular cell adhesion molecule. The function of this molecule has been further evaluated by transfecting cells with a full-length PECAM-1 cDNA. Transfected COS-7, mouse 3T3 and L cells expressed a 130-120-kD glycoprotein on their cell surface that reacted with anti-PECAM-1 polyclonal and monoclonal antibodies. COS-7 and 3T3 cell transfectants formed cell-cell junctions that were highly enriched in PECAM-1, reminiscent of its distribution at endothelial cell-cell borders. In contrast, this protein remained diffusely distributed within the plasma membrane of PECAM-1 transfected cells that were in contact with mock transfectants. Mouse L cells stably transfected with PECAM-1 demonstrated calcium-dependent aggregation that was inhibited by anti-PECAM antibodies. These results demonstrate that PECAM-1 mediates cell-cell adhesion and support the idea that it may be involved in some of the interactive events taking place during thrombosis, wound healing, and angiogenesis.

Albelda, S. M., Muller, W. A., Buck, C. A., & Newman, P. J. (1991). Molecular and cellular properties of PECAM-1 (endoCAM/CD31): a novel vascular cell-cell adhesion molecule. The Journal of Cell Biology, 114(5), 1059–1068.