title: Rapid isolation and biochemical characterization of rat C1 and C1q.
abstract: Using a human IgG-Sepharose column to which rabbit anti-human IgG was bound (rabbit anti-human/human IgG-Sepharose), human and rat C1 or C1q were isolated from serum in a single step, and the C1q further purified to homogeneity by FPLC. This procedure allowed the rapid isolation of haemolytically active C1 or C1q, with a yield equal to or greater than published methods. The availability of human and rat C1q allowed comparison of the two molecules, revealing differences in their mobility on SDS-PAGE as well as on agarose gel electrophoresis. Amino terminal sequence analysis demonstrated greater than 78% residue identity between rat C1q A, B and C chains and the published human and mouse sequences. Similar amino acid compositions suggest that the homology extends throughout the molecules. In addition to the major A:B and C:C dimer bands, rat, unlike human C1q, contained minor dimer species. These may reflect heterogeneity in glycosylation and or lysine and proline hydroxylation.
authors: Molecular Immunopathology Unit, MRC Centre, Cambridge, U.K.
authors: M G
authors: MG
authors: Wing
authors: D J
authors: DJ
authors: Seilly
authors: D J
authors: DJ
authors: Bridgman
authors: R A
authors: RA
authors: Harrison
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002847:Chromatography, Agarose; D002852:Chromatography, Ion Exchange; D003172:Complement C1 / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*; D015922:Complement C1q / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*; D015941:Complement Hemolytic Activity Assay; D004587:Electrophoresis, Agar Gel; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D008969:Molecular Sequence Data; D051381:Rats; D017386:Sequence Homology, Amino Acid
chemical_list: D000596:Amino Acids; D003172:Complement C1; D015922:Complement C1q