Biosynthesis and processing of pro-C3, a precursor of the third component of complement in rat hepatocytes: effect of secretion-blocking agents.
Biosynthesis and intracellular processing of the third component (C3) of complement were studied in cultured rat hepatocytes. In the control cells, the complement C3 was synthesized as a pro-form, a single polypeptide chain comprising both the alpha- and beta-subunits. Although the cleavage of the pro-form into the subunits was not clearly demonstrable within the cells during pulse-chase periods, all the secreted C3 was the mature processed form. The cells were treated with secretion-blocking agents with different modes of action, colchicine and monensin. Colchicine caused an accumulation of the processed C3 within the cells, whereas monensin blocked the secretion without a significant accumulation of the processed form. The results indicate that the conversion of the C3 pro-form into the subunits takes place in the secretory vesicles just before the secretion.
D000818:Animals; D002478:Cells, Cultured; D003078:Colchicine / Q000494:pharmacology*; D003176:Complement C3 / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D005663:Furans / Q000494:pharmacology*; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D046911:Macromolecular Substances; D008297:Male; D008985:Monensin / Q000494:pharmacology*; D011498:Protein Precursors / Q000096:biosynthesis* / Q000235:genetics; D051381:Rats; D011919:Rats, Inbred Strains; D013462:Sulfur Radioisotopes
D003176:Complement C3; D005663:Furans; D046911:Macromolecular Substances; D011498:Protein Precursors; D013462:Sulfur Radioisotopes; D008985:Monensin; D003078:Colchicine