CD46 (MCP), Human, mAb M160

The monoclonal antibody M160 recognizes CD46, also designated membrane cofactor protein (MCP). CD46 is a 45- 70 kDa protein with genetic and tissue-specific heterogeneity. It is expressed on every cell and tissue, with the exception of erythrocytes. CD46 serves to inhibit complement activation on host tissue. It performs this function by serving as a cofactor which binds to C3b and C4b. This binding is permitted by factor I, a serine protease of plasma, to degrade C3b and C4b and serves to protect the host cell against autologous attack. It also serves as a receptor for measles virus. Four isoforms of CD46 predominate and arise by alternative splicing of a single CD46 gene. CD46 cDNA encodes a signal sequence followed by four complement control protein domains (also called short consensus repeats (SCR)). The monoclonal antibody M160 reacts with the SCR2 domain.