Phosphorylation-dependent epitopes of neurofilament antibodies on tau protein and relationship with Alzheimer tau.

Abstract

We have studied the phosphorylation of tau protein from Alzheimer paired helical filaments, of tau from normal human brain, and of recombinant tau isoforms. As a tool we used monoclonal antibodies against neurofiamentProc. Nad. Acad. Sci. USA 82, 4274-4276] that crossreact with tau in a phosphorylation-dependent manner. This allowed us to deduce the state of phosphorylation in normal and pathological tau, as well as antibody epitopes. The epitope of antibody SM133 is at the first Lys-Ser-Pro sequence motif (residues 234-236) and requires an unphosphorylated Ser-235. Antibody SMI31 binds between Ser-396 (in the second Lys-Ser-Pro motif) and Ser-404, both of which must be phosphorylated. SM134 has a conformational epitope that depends on the interaction between regions on either side of the microtubule-binding

Localisation of Microtubule‐Associated Protein 1B Phosphorylation Sites Recognised by Monoclonal Antibody SMI‐31

“…These conclusions are consistent with previous studies on the properties of the mAb SMI-3 1 epitope in neurofibaments and tau proteins (Lichtenberg-Kraag et al, 1992;Doroudchi and Durham, 1996). For example, in neurofilaments, mAb SMI-3 1 recognises phosphorylated epitopes at KSP sites on the Cterminal domain (Doroudchi and Durham, 1996).…”

“…Therefore, it is possible that the mAb SMI-31 epitope was disrupted by NTCB cleavage. A conformational component to the mAb SMI-31 epitope present on tau has been reported (Lichtenberg-Kraag et al, 1992), suggesting that a cleavage site need not cut through the epitope to affect antibody recognition. In contrast, the GST-1B750 sequence contains only one cysteine residue, distant from the site localised as the mAb SMI-3l epitope in this report, making disruption of this site less likely.…”

“…mAb SMI-31 also recognises phosphorylation epitopes on tau and the high and intermediate weight proteins of neurofilaments (Sternberger and Sternberger, 1983;Lichtenberg-Kraag et al, 1992;Ulba et al, 1993) and these epitopes contain serine! proline sites (Lichtenberg-Kraag et al, 1992;Doroudchi and Durham, 1996).…”

“…For example, in neurofilaments, mAb SMI-3 1 recognises phosphorylated epitopes at KSP sites on the Cterminal domain (Doroudchi and Durham, 1996). In tau, mAb SMI-31 binds between Ser 396 (in the second KSP motif) and Ser404, both of which must be phosphorylated (Lichtenberg-Kraag et al, 1992). In addition, western blot analysis showed that tau epitopes phosphorylated by cdc2 kinase are recognised by mAb SMI-3l (Hosoi et al, 1995).…”

Dephosphorylation of tau protein and Alzheimer paired helical filaments by calcmeurin and phosphatase‐2A

“…The findings reported here were initially triggered by the observation that an extract prepared from mammalian brain possesses a kinase activity towards tau that induces the Alzheimer-like antibody reactivity (by phosphorylating mostly SP and TP motifs; [4,29]) and reduces microtubule interactions by phosphorylating Se?2 [5]. But it was also clear that phosphatases played an important role since efficient phosphorylation was achieved only in the presence of phosphatase inhibitors [17].…”