title: cDNA clone spanning the alpha-gamma subunit junction in the precursor of the murine fourth complement component (C4).
abstract: cDNA clones carrying parts of murine fourth complement component (C4, serum substance protein) mRNA sequences have been identified by differential hybridization to mRNA from a high C4-producing strain, B10.WR, and a congeneic low C4 strain, B10.BR, followed by hybrid-selected translation and DNA sequence analysis. One clone, pMLC4/w7-2, encodes an open amino acid reading frame that includes four tandem arginine residues immediately preceding a sequence 85% homologous with the NH2-terminal sequence of the human C4 gamma-chain. The amino acid composition of the predicted sequence upstream of the tandem arginines matches quite closely with the composition of a similar sized peptide at the COOH terminus of the human C4 alpha chain. The latter result raises questions regarding the nature and extent of plasma-mediated postsynthetic processing of the C4 alpha-chain COOH terminus. The results also demonstrate that strain differences in plasma C4 levels (low C4 vs. high C4) reflect differences in steady-state levels of liver C4 mRNA in these strains.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D003181:Complement C4 / Q000235:genetics*; D004247:DNA / Q000378:metabolism*; D006801:Humans; D008099:Liver / Q000276:immunology; D046911:Macromolecular Substances; D051379:Mice; D008815:Mice, Inbred Strains; D009693:Nucleic Acid Hybridization; D011061:Poly A / Q000235:genetics; D014176:Protein Biosynthesis; D012313:RNA / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism
chemical_list: D003181:Complement C4; D046911:Macromolecular Substances; D012333:RNA, Messenger; D011061:Poly A; D012313:RNA; D004247:DNA