Cb. Caputo et al., IMMUNOLOGICAL CHARACTERIZATION OF THE REGION OF TAU-PROTEIN THAT IS BOUND TO ALZHEIMER PAIRED HELICAL FILAMENTS, Neurobiology of aging, 13(2), 1992, pp. 267-274
Tau protein is known to be present in the paired helical filaments (PH
Fs) of Alzheimer brains. This study investigated the fragments of tau
protein that remain bound to pronase-treated PHFs and conditions that
lead to the release of these tau fragments from the core structure of
the PHF. Antibody 423 reacted with PHFs and with fetal rat tau but not
with adult rat tau, pig tau, or recombinant human tau. Three other an
tibodies that react with the tubulin binding region of tau only reacte
d with PHFs after they were disrupted with formic acid or guanidine. O
ther antibodies that recognize tau sequences C terminal to the tubulin
binding region also recognized pronase-treated PHFs. Antibodies SM134
and T3P that recognize phosphorylated epitopes were reactive with pro
nase-treated PHFs. Tau fragments from the PHF were solubilized by acid
or guanidine treatment. These findings suggest that the fragments of
tau that are bound to PHFs and protected from pronase digestion includ
e sequences from the tubulin binding region to the C terminus of tau.
In addition, some of these sequences appear to be conformationally or
post-translationally modified.