This protein is a cell adhesion molecule expressed on platelets and at endothelial cell intercellular junctions. Type I membrane protein. SIZE: 738 amino acids; 82536 Da. SUBCELLULAR LOCATION: Membrane; Single-pass type I membrane protein. TISSUE SPECIFICITY: Long isoform predominates all tissues examined，isoform Delta12 was detected only in trachea and isoform Delta14-15 only in lung，isoform Delta14 was detected in all tissues examined with the strongest expression in heart. PTM: Phosphorylated on Ser and Tyr residues after cellular activation. SIMILARITY: Contains 6 Ig-like C2-type (immunoglobulin-like) domains.CD31，also known as platelet endothelial cell adhesion molecule 1 (PECAM1)，is a type I integral membrane glycoprotein and a member of the immunoglobulin superfamily of cell surface receptors. It is found on the surface of platelets，monocytes，neutrophils，and some types of T-cells，and makes up a large portion of endothelial cell intercellular junctions. CD31 is implicated in several func