Human Membrane Cofactor Protein (CD46) Protein

Background

CD46, also known as membrane cofactor protein (MCP), is a transmembrane glycoprotein that serves primarily as a regulatory component of the complement system, protecting host cells from complement-mediated damage. CD46 is widely expressed on almost all nucleated cells and plays a key role in immune regulation, ensuring that the complement system, which is responsible for clearing pathogens, does not attack the body’s own cells. CD46 does this by serving as a cofactor for the proteolytic cleavage of C3b and C4b, two crucial components of the complement pathway, which are inactivated by factor I. In addition to its role in the complement system, CD46 is involved in various immune functions, including modulation of T-cell responses, immune tolerance, and viral entry. Several viruses, such as the measles virus and human herpesvirus 6 (HHV-6), use CD46 as a receptor to gain entry into host cells, highlighting its involvement in viral pathogenesis.