title: Biosynthesis of pro-C3, a precursor of the third component of complement.
abstract: A precusor of the third component of complement, pro-C3, was detected in studies of cell-free synthesis and intracellularly in homogenates of liver tissue cultures. The molecular weight of pro-C3 was indistinguishable from that of intact native C3 secreted in vitro by liver or peritoneal macrophages, but its structure was different. Pro-C3 is a single polypeptide chain, whereas C3 secreted by cells in culture consists of two polypeptide chains (mol wt 120,000 and 76,000) linked by disulfide bonds.
mesh_terms: D000818:Animals; D002474:Cell-Free System; D003176:Complement C3 / Q000096:biosynthesis*; D003165:Complement System Proteins / Q000096:biosynthesis*; D006168:Guinea Pigs; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism; D008970:Molecular Weight; D011498:Protein Precursors / Q000096:biosynthesis*
chemical_list: D003176:Complement C3; D011498:Protein Precursors; D003165:Complement System Proteins