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Monoclonal antibody PHF‐9 recognizes phosphorylated serine 404 of tau protein and labels paired helical filaments
Author(s) -
Zemlan Frank P.,
Dean Gary E.
Publication year - 1996
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/(sici)1097-4547(19961001)46:1<90::aid-jnr11>3.0.co;2-g
Subject(s) - phosphorylation , epitope , cyanogen bromide , chemistry , monoclonal antibody , peptide , microbiology and biotechnology , serine , biochemistry , peptide sequence , antibody , biology , immunology , gene
Paired helical filaments (PHFs) purified from Alzheimer's brain consist of hyperphosphorylated microtubule‐associated protein tau. In PHF, phosphorylation occurs at ser/thr tau residues. Several of these ser/thr phosphorylation sites lie immediately C‐terminal to the tau tubulin binding domain. The C‐terminal ser 396 to thr 413 tau region contains two or more phosphorylated residues and eight possible ser/thr phosphorylation sites. Immunologic studies and mass spectroscopy have identified ser 396 as one of the phosphorylation sites but identification of more C‐terminal phosphorylated residues has been hampered by the lack of monoclonal antibodies (Mabs) that recognize defined epitopes in this region. We have raised Mabs against PHF purified from Alzheimer's brain. One of these Mabs, PHF‐9, showed phosphorylation‐dependent binding to purified PHF and recognized a phosphorylated epitope in the C‐terminal portion of cyanogen bromide‐digested PHF. Epitope mapping studies employing synthetic tau phosphopeptides indicated that PHF‐9 labeled a 13‐mer tau peptide phosphorylated at ser 404 but not the corresponding non‐phosphorylated peptide. PHF‐9 demonstrated no immunoreactivity with a synthetic peptide phosphorylated at ser 396 indicating that the PHF‐9 epitope is C‐terminal to ser 396 . In conclusion, the present study describes a Mab, PHF‐9, which recognizes phosphorylated ser 404 of tau independently of phosphorylated ser 396 and indicates that tau ser 404 is phosphorylated in PHF. © 1996 Wiley‐Liss, Inc.