CHARACTERIZATION OF TAU-PROTEIN PRESENT IN MICROTUBULES AND PAIRED HELICAL FILAMENTS OF ALZHEIMERS-DISEASE PATIENTS BRAIN

Two proteins immunologically related to porcine tau protein are found in the brain of Alzheimer's disease patients. One is bound to microtubules and, after isolation by co-polymerization with tubulin, shows a size and tryptic peptide map, similar to the microtubule-associated tau protein, present in the brain of non-demented patients. The other tau-related protein is present as the major protein of a purified fraction of paired helical filaments. The paired helical filament-associated protein shows smaller molecular weight (33,000) than microtubule-associated tau; however, this 33,000 mol. wt protein reacts with a monospecific anti-tau antibody and with an antibody to a 19-amino acid peptide corresponding to amino acids 228-246 of human tau. Furthermore, the 33,000 mol. wt protein and the tau protein have similar tryptic peptide maps. These results suggest that the paired helical filament protein is a modified form of the microtubule-associated tau protein. © 1990.