Clone REA396 recognizes the rat CD31 antigen, a 130 kDa single-pass type I membrane protein also known as platelet endothelial cell adhesion molecule (PECAM-1). CD31 is a homophilic receptor that is expressed by endothelial cells, platelets, granulocytes, macrophages, dendritic cells, T and B cells, and natural killer cells. There are several spliced variants of CD31 – expressed in a cell-type- and species-specific manner in human, mouse, and rat – that arise as a result of alternative splicing of either the transmembrane, or one of the cytoplasmic tail exons. In addition to its well-known homophilic interaction, a number of putative heterotypic ligands for CD31 have also been identified, including the neutrophil-specific antigen CD177 and the ADP-ribosyl cyclase CD38. The homophilic nature of CD31 facilitates its engagement with other CD31-expressing cells, and this includes leukocyte–leukocyte interactions. For instance, T and B cells need to interact with each other and with antigen-presenting cells to mature or become activated. The presence of CD31 is also crucial in establishing interactions of lymphocytes with the endothelium or with platelets to modulate immune responses at the vascular wall and for the recruitment or extravasation of immune cells in inflamed tissues. CD31 has been shown to inhibit antigen receptor signaling in T and B cells through the action of protein-tyrosine-phosphatases.
Additional information: Clone REA396 displays negligible binding to Fc receptors.