The extent of phosphorylation of fetal tau is comparable to that of PHF-tau from Alzheimer paired helical filaments.
The relationship between Alzheimer's disease (AD) and expression of fetal proteins was examined by: (i) determining the phosphate content of tau prepared from fetal brains (F-tau); (ii) comparing F-tau, tau from normal adult human brains (N-tau) and tau from paired helical filaments in AD brains (PHF-tau) for phosphate content; and (iii) testing the reactivity of F-tau with five antibodies known to recognize PHF-tau. The antibodies have been reported to recognize phosphate dependent epitopes at the carboxy-terminal half of the tau molecule. Our data shows that on the average, F-tau contains 7 mol phosphate/mol protein, which is comparable to the phosphate content of PHF-tau, but is 3-4 times higher than that of N-tau. Immunoblotting shows that all of the tested antibodies reacted with F-tau on immunoblots, indicating that F-tau and PHF-tau are phosphorylated at similar sites. A difference between PHF-tau and F-tau is the state of phosphorylation in the Tau-1 epitope, an epitope reactive with a monoclonal anti-tau antibody, Tau-1. This epitope, which is phosphorylated in all PHF-tau, is phosphorylated only in some of the F-tau. The sharing of phosphorylated sites between F-tau and PHF-tau has also been reported by others in studies with antibodies to different and similar phosphorylated epitopes. Together these observations indicate that the extent and the site of phosphorylation in F-tau and PHF-tau tau are similar.(ABSTRACT TRUNCATED AT 250 WORDS)
Kenessey
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A
Department of Pathology, Albert Einstein College of Medicine, Bronx, NY 10461.
Yen
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SH
D000022:Abortion, Spontaneous; D000328:Adult; D000469:Alkaline Phosphatase; D000544:Alzheimer Disease / Q000378:metabolism*; D001921:Brain / Q000196:embryology* / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005333:Fetus; D006801:Humans; D015151:Immunoblotting; D016874:Neurofibrillary Tangles / Q000378:metabolism* / Q000473:pathology; D010766:Phosphorylation; D011247:Pregnancy; D016875:tau Proteins / Q000302:isolation & purification / Q000378:metabolism*
D016875:tau Proteins; D000469:Alkaline Phosphatase