title: Specific recognition of protein carboxy-terminal sequences by natural IgM antibodies in normal serum.
abstract: Our previous study indicated that normal serum contains complement-fixing natural IgM antibodies reacting with a large variety of randomly generated protein carboxy-termini. Here we show that the "carboxy-terminal" IgM (C-IgM) antibodies specifically react with short peptide sequences located immediately at the protein carboxy-terminus. The specificity of C-IgM-peptide interactions is tentatively defined by three to four amino acid residues. All carboxy-terminal peptides in a large peptide library apparently react with C-IgM antibodies. Immobilized synthetic peptides also react with C-IgM antibodies. No interaction of C-IgM antibodies with internal peptide sequences has been observed. C-IgM antibodies are present in germ-free and in athymic adult rats and are absent in newborn rats. The natural ubiquity of protein carboxy-termini in biological structures suggests that C-IgM could play an important role in antigen clearance and presentation to the immune system. From a practical viewpoint, the recognition of carboxy-terminal peptides by complement-fixing C-IgM antibodies has profound implications for the use of peptide- and protein-derivatized delivery vehicles and artificial materials.
authors.affiliation: Department of Pediatrics, University of Wisconsin, Madison, Wisconsin 53705, USA.
authors.forename: A V
authors.initials: AV
authors.lastname: Sokoloff
authors.forename: I
authors.initials: I
authors.lastname: Bock
authors.forename: G
authors.initials: G
authors.lastname: Zhang
authors.forename: S
authors.initials: S
authors.lastname: Hoffman
authors.forename: J
authors.initials: J
authors.lastname: Dama
authors.forename: J J
authors.initials: JJ
authors.lastname: Ludtke
authors.forename: A M
authors.initials: AM
authors.lastname: Cooke
authors.forename: J A
authors.initials: JA
authors.lastname: Wolff
mesh_terms: D000818:Animals; D000917:Antibody Formation; D000918:Antibody Specificity; D000937:Antigen-Antibody Reactions / Q000276:immunology; D017123:Bacteriophage T7 / Q000235:genetics; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology; D004926:Escherichia coli / Q000235:genetics; D005822:Genetic Vectors; D007075:Immunoglobulin M / Q000276:immunology*; D008024:Ligands; D010446:Peptide Fragments / Q000235:genetics / Q000276:immunology*; D019151:Peptide Library; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000939:Epitopes; D007075:Immunoglobulin M; D008024:Ligands; D010446:Peptide Fragments; D019151:Peptide Library