Fig. 4

Summary for compensatory role of C3 convertase on the cleavage pathway of C3 protein. C3 convertase, comprising the C4b and C2b fragments, leads to the production of C3a and C3b. Additional deposited C3b forms the C5 convertase, which reacts with other complement factors to form membrane attack complex (MAC). Abbreviations: +, low level of expression; ++, medium level of expression; +++, high level of expression