Figure 1

Glycoprotein binding and complement activation by CL-K1. A) Immunoblot of CL-K1 binding to immobilised mammalian and yeast glycoproteins. B) Surface plasmon resonance of CL-K1 binding to glycoproteins. CL-K1 was immobilised on the chip surface (6,000 response units) and six two-fold dilutions of each glycoprotein were injected at a starting concentration of 200 nM. C) Complement component C3b was measured on mannan following incubation with human serum, depleted of endogenous lectins, and supplemented with either CL-K1 or human recombinant MBL. C3b and its breakdown products were detected by absorbance using an anti-human C3c antibody with alkaline phosphatase-conjugated goat anti-rabbit secondary antibody and p-nitrophenyl phosphate as the substrate. Protein concentrations were calculated based on the molecular masses of CL-K1 and MBL trimers (78 kDa in each case). CL-K1, collectin-K1; MBL, mannan-binding lectin.