Clone REA312 recognizes the human CD46 antigen, a type I transmembrane glycoprotein, which is also known as the membrane cofactor protein (MCP). At least fourteen different transcript variants encoding different isoforms have been found for CD46. It is expressed by a broad range of tissues including leukocytes, platelets, epithelial cells, and fibroblasts, but not by erythrocytes. CD46 acts as a co-factor for complement factor I, a serine protease which protects autologous cells against complement-mediated injury by cleaving C3b and C4b deposited on host tissue. It is involved in the fusion of the spermatozoa with the oocyte during fertilization. Additionally, CD46 functions as a receptor for measles virus, human herpesvirus, and human adenovirus. It is a potent costimulator for the induction of interferon-γ secreting effector T helper type 1 cells and their subsequent switch into interleukin 10 producing regulatory T cells. 

Additional information: Clone REA312 displays negligible binding to Fc receptors.