An antiserum against amyloid β-protein precursor detects a unique peptide in Alzheimer brain

An antiserum was raised against an amino acid sequence predicted from the DNA sequence of amyloid β-protein precursor (ABPP), and it was then affinity-purified. This affinity-purified antibody (anti-GID) intensely stained neurons and dystrophic neurites in plaques of Alzheimer's disease (AD) patients, but marginally stained neurons of age-matched normal individuals. Anti-GID antibody detected a series of protein bands with a molecular weight centered at 100,000 and a second band at 55,000 on a blot of the human brain particulate fraction. It also stained a set of bands with a molecular weight around 95,000 and a doublet of M_r 16,000 in the soluble fraction. A band at M_r 35,000 was detected in the soluble fraction prepared from brain tissue of AD patients but not from control brain tissue. A strong immunostaining of AD sections with anti-GID and the presence of a M_r 35,000 band unique to AD might reflect an altered processing of ABPP in AD brains