Complement Component 5 (C5)

Complement component 5 (C5) is a crucial protein in the human complement system, an essential part of innate immunity. It is encoded by the C5 gene and plays a central role in inflammation, host defense, and cell lysis. Cleavage of C5 by specific proteases called "C5 convertases" produces two fragments: C5a (a potent anaphylatoxin) and C5b (initiates assembly of the membrane attack complex (MAC)). Deficiency or mutations in the *C5* gene can cause increased susceptibility to severe recurrent infections. Inhibitors targeting cleavage or function of C5 have been developed for clinical use, such as Eculizumab, which blocks cleavage into pro-inflammatory fragments.

Inhibition of C5 cleavage into C5a and C5b