Proteolytie Cleavage of C4.C3.and C5 Molecules c国 C3 Convertase 462h3 Y Chain o Chain Chain a Chain B Chain anaphylatoxic activity opsonization activity Membrane Attack Complex (MAC) C9 (10 to 18 molecules) membrane membrane pore10 Transmembrane Channel formed by C9 polymers Classical Complement Pathway. The classical complement pathway requires the presence of antibodies,either as immunoglobulin (IgG or IgM)bound to cell surface Ag or as an Ag-Ab immune complex The serum proteinCl binds to the antibody,which in turn results in activation of C4,C2,and C3,and leads to the formation of C5,C6,C7,C8 and C9.This eventuallyClassical Complement Pathway. The classical complement pathway requires the presence of antibodies, either as immunoglobulin (IgG or IgM) bound to cell surface Ag or as an Ag-Ab immune complex. The serum protein C1 binds to the antibody, which in turn results in activation of C4, C2, and C3, and leads to the formation of C5, C6, C7, C8 and C9. This eventually