Fig. 2
Schematic representation of the structure of several complement inhibitors. The protein motif structure of many of the complement inhibitors described in the text are shown here. Most of the inhibitors that block activation of complement through the C3 convertases are composed of short-census repeat (SCR) protein motifs. Each SCR is approximately 60 to 70 amino acids long and contains four cysteine residues that are disulfide bonded within each SCR (cysteine 1 to cysteine 3 and cysteine 2 to cysteine 4). The result is a rod-like, elongated structure, although there is considerable flexibility in the overall structure. For a more detailed discussion of these structures, see references listed in the text. LHR, long homologous repeat; sLex, sialyl Lewis X.