Effect of the Complement-activating Bactericidal Factor, Ra-reactive factor, on the Activation of Serine Protease in Mouse Peritoneal Phagocytes

概要

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RaRF is a complement-activating bactericidal factor present in sera of various vertebrates. It binds to Ra core polysaccharide of enterobacteria and a serine protease, P100, in the RaRF molecule kills these bacteria by inducing the activation of the C4 and C2 components of complement. To find a possible role of RaRF in lysosomal enzymes of phagocytes, mouse peritoneal macrophages were treated with RaRF-coated fluorescent beads, and the change in molecular sizes of serine proteases in the cell extracts was examined by SDS-PAGE. Serine proteases were labelled with [^3H] diisopropylfluorophosphate and detected by autoradiography after the SDS-PAGE. The DFP-binding proteins of 32 kDa and 38 kDa were present in the extracts of macrophages. It was found that amount of the 38-kDa DFP-binding protein decreased significantly when the macrophages engulfed the RaRF-coated beads, while BSA- and HGG-coated beads have no effect of decreasing the 38-kDa protein. These results suggest that the P100 of RaRF, which is engulfed by macrophages, cleaves the 38-kDa serine protease precursor in cells, generating the 32-kDa mature enzyme.
北里大学の論文
1994-12-31