C5

fifth cervical nerve; fifth cervical vertebra; fifth component of complement activated fifth component of complement

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a complement component that binds to the C3b component of both the classical and alternative pathway C5 convertases (C4b,2a,3b and C3b_n,P,Bb), being split by either convertase into the smaller anaphylatoxin C5a and the larger cell surface–bound C5b, the initial component of the membrane attack complex.