- C3 and C5 Convertases: These are enzyme complexes that cleave _C3_ and _C5_, respectively, into their active forms, C3a, C3b, C5a, and C5b. C3b and C5b play crucial roles in _opsonization_ and the formation of the _membrane attack complex_ (MAC). - C3a and C5a: These are anaphylatoxins that increase vascular permeability and attract phagocytes to the site of infection. - Membrane Attack Complex (MAC): Formed by the assembly of C5b, C6, C7, C8, and C9, the MAC creates pores in the pathogen's membrane, leading to cell lysis.
