Platelet Agonist F11 Receptor Is A Member Of The Immunoglobulin Superfamily And Identical With Junctional Adhesion Molecule (Jam): Regulation Of Expression In Human Endothelial Cells And Macrophages

The stimulatory mAb F11 binds two platelet membrane proteins of 32 and 35 kDa and causes activation of platelets when crosslinked with the Fc gamma RII receptor. We used bioinformatics to identify expressed sequence tags from libraries of cytokine-stimulated human endothelial cell (EC) cDNAs, The protein sequence deduced from full-length F11 cDNA was identical to partial sequences of peptides derived from affinity-purified platelet F11 antigen. F11 mRNA is expressed in human EC, macrophages, and a variety of non-hematopoietic vascular tissues. Expression of F11 mRNA is modulated by cytokines in EC and is up-regulated by oxidized low-density lipoprotein in human macrophages, The F11 receptor contains two immunoglobulin-like domains in its 236-amino-acid-long extracellular region, and has identity to the recently described junctional adhesion molecule. The data indicate that the F11 antigen is a novel receptor or cell adhesion molecule belonging to the immunoglobulin superfamily.