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Specific recognition of protein carboxy-terminal sequences by natural IgM antibodies in normal serum.

Molecular therapy : the journal of the American Society of Gene Therapy (2001-06-16)
A V Sokoloff, I Bock, G Zhang, S Hoffman, J Dama, J J Ludtke, A M Cooke, J A Wolff
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.

MATERIALS
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Brand
Product Description

Sigma-Aldrich
Anti-Human IgM (μ-chain specific)−Alkaline Phosphatase antibody produced in goat, affinity isolated antibody, buffered aqueous solution