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. Author manuscript; available in PMC: 2010 Sep 1.
Published in final edited form as: Mol Immunol. 2009 Aug 5;46(15):2902–2910. doi: 10.1016/j.molimm.2009.07.006

Fig. 1.

Fig. 1

Inhibition of formation of the lectin pathway C3/C5 convertase by C4BP on zymosan and EMan cells measured as the amount of C5 convertase activity remaining. (A) The C3 convertase was allowed to form on zymosan particles bearing 346,000 C4b/Zym while the C5 convertase was assembled on zymosan bearing 54,000 C4b and 362,000 C3b per zymosan in the presence of indicated concentration of C4BP. Inhibition of enzyme formation was measured as the amount of C5 convertase activity remaining by determining the amount of C5b,6 formed using hemolytic assay with EC. C5b,6 formed in the absence of C4BP was considered 100%. To obtain IC50, the data were fit by nonlinear regression using Grafit version 5.0 Erithacus software. Vertical bar indicates the normal concentration range of C4BP in plasma (250-400 nM). Symbols: soluble C3 convertase C4b,C2a (Δ); surface-bound C3 convertase, ZymM1,C4b,C2a (○); surface-bound C5 convertase, ZymM1,C3bC4b,C2a (●). (B). Inhibition of formation of the lectin pathway C3/C5 convertase on EMan cells by C4BP. Experimental details are as described above in A except that EMan cells bearing 471,000 C4b/EMan were employed to assemble the C3 convertase while cells bearing 138,000 C4b and 110,000 C3b per EMan were used for assembling the C5 convertase. Symbols: soluble C3 convertase, C4b,C2a(Δ); surface-bound C3 convertase, EManM1,C4b,C2a (○); surface-bound C5 convertase, EManM1,C3bC4b,C2a (●).