Functional evaluation of the C3 mutations: cofactor activity. The cofactor activity of FH or MCP toward the cleavage of the recombinant mutant C3 proteins by FI was assessed by western blot. The appearance of the α41 band indicates the cleavage. (A) Representative image for FH. (B) Representative image for MCP. (C) Representative image for CR1. (D). Example for the quantification of the western blot for CR1. (E) Two-dimensional plot representing the fraction of cofactor activity remaining relative to WT for MCP vs FH for each mutation. The dashed lines indicate the cofactor activity in case of WT, and the solid lines represent the 25% confidence limits below which the decrease was considered relevant for the disease. (F) Two-dimensional plot representing the fraction of WT binding for MCP vs FH for each mutation as shown in Figures 2 and 3. The dashed lines indicate the WT binding, and the solid lines represent the 25% confidence limits below which the decrease of the binding was considered relevant for the disease.