τ in Paired Helical Filaments Is Functionally Distinct from Fetal τ: Assembly Incompetence of Paired Helical Filament‐τ

Abstract

tau in paired helical filaments (PHF-tau) and fetal tau share several phosphorylated epitopes, as revealed by several phosphorylation-dependent PHF monoclonals. We have asked whether there is any difference between the two molecules in tubulin assembly-promoting activity and found that PHF-tau is almost assembly incompetent, whereas fetal tau is low in this activity but still assembly competent. This indicates that despite substantial similarities in immunoreactivities, PHF-tau and fetal tau are quite distinct from each other in function.