Demonstration of a 72 K β-protein precursor fragment in Alzheimer and normal aged brain

Abstract
To identify the components of amyloid precursor protein (APP) in brain, studies were performed using an immunoblotting method on Alzheimer and control brains with antibodies to synthetic peptides consisting of subsequences of APP. Immunoblots of brain homogenates detected an immunoreactive protein with a molecular weight of 72 K. There was no difference in the patterns of immunoreactive bands when comparing normals and Alzheimer''s disease. This protein was recognized by both anti-.beta.-peptide and anti-APP C-terminal antibodies, suggesting that this is a stable intermediate that is further processed by proteolysis to form amyloid.