Guinea pig macrophages synthesize a low molecular weight form of C1q with affinity for the C1r2C1s2-complex but which does not bind to Fc in immunoglobulin aggregates.
Biosynthetically labelled C1q secreted by guinea pig peritoneal macrophages was analysed by sedimentation through sucrose gradients followed by SDS-PAGE. In addition to the haemolytically active C1q of mol. wt 460,000 Da a low mol. wt (LMW) form of C1q was identified which had no detectable affinity for Fc of aggregated immunoglobulin, but which retained the ability to associate with the C1r2s2-complex. This LMW-C1q was covalently associated with two additional polypeptides of mol. wt 46 and 50 kDa.
Martin
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Institute für Medizinische Mikrobiologie, Augustusplatz/Hochhaus, Mainz, F.R.G.
Loos
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D000818:Animals; D002499:Centrifugation, Density Gradient; D003166:Complement Activating Enzymes / Q000096:biosynthesis* / Q000276:immunology / Q000378:metabolism*; D003172:Complement C1 / Q000096:biosynthesis* / Q000276:immunology / Q000378:metabolism*; D015922:Complement C1q; D015923:Complement C1r; D003173:Complement C1s / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006168:Guinea Pigs; D006461:Hemolysis; D007141:Immunoglobulin Fc Fragments / Q000276:immunology*; D008264:Macrophages / Q000276:immunology*; D008297:Male; D008970:Molecular Weight
D003172:Complement C1; D007141:Immunoglobulin Fc Fragments; D015922:Complement C1q; D003166:Complement Activating Enzymes; D015923:Complement C1r; D003173:Complement C1s