C3b binds to the C3 convertase (C4b2a), to form C5 convertase (C4b2b3bC4b2a3b). C5 convertase then cleaves C5 into C5a and C5b.<ref name="Complement history" /> Like C3a, C5a is also an anaphylatoxin that interacts with its cognate C5a receptor (C5aR) to attract leukocytes.<ref name="Overview of Complement" /> Subsequent interactions between C5b and other terminal components C6, C7, C8, and C9 form the membrane attack complex or the C5b-9 complex which forms pores on the target cell membranes to lysing.<ref name="Rus 103–112">{{Cite journal| last1 = Rus| first1 = Horea| last2 = Cudrici| first2 = Cornelia| last3 = Niculescu| first3 = Florin| date = 2005-11-01| title = The role of the complement system in innate immunity| journal = Immunologic Research| language = en| volume = 33| issue = 2| pages = 103–112| doi = 10.1385/IR:33:2:103| issn = 0257-277X| pmid=16234578| s2cid = 46096567}}</ref>
