Binding of IgG to amyloid βA4 peptide via the heavy-chain hinge region with preservation of antigen binding

Abstract Amyloid β A4 peptide is found in the extracellular region of the senile plaque and in the angiopathy of Alzheimer's disease. Several other proteins, including IgG, also reside in these abnormal structures. In an attempt to understand how these structures are assembled and to determine how proteins are recruited, interactions of various proteins with synthetic β A4 peptide have been examined in vitro. Purified IgG binds directly ti synthetic β A4 peptide with high avilidity. The domain between amino acids 12–28 of β A4 peptide binds the hinge region of the immunoglobulin heavy chain, and preserves the ability of the immunoglobulin to bind antigen. A protein which does not bind directly to β A4 peptide can be targetted tot he senile plaque and angiopathy by binding to IgG, which avidly binds β A4 peptide.