HMW Isoforms Research Articles

Preparation of Tau from the Periphera -Nerve: Presence of Insoluble Low Molecular Weight Tau with High Phosphorylation

Purely axonal tau protein of the peripheral nervous system (PNS) obtained from adult rat ventral roots was composed of both high (HMW) and low molecular weight (LMW) isoforms. While the PNS-specific HMW isoform (110 kDa) was soluble, 60-70% of the LMW isoforms with apparent molecular weights of 67 kDa, 62 kDa and 58 kDa was insoluble. When analyzed by two-dimensional electrophoresis, these axonal LMW isoforms corresponded to the most acidic species among the large number of isoforms found in brain microtubule-associated tau. Immunoreactivities towards phosphorylation-dependent antibody tau-1 and the two antiphosphopeptide antibodies (PP1 and PP2) indicate that PNS axonal tau is highly phosphorylated at Ser 190, Ser 193, and Ser 387, which are the sites shown to be phosphorylated in fetal. brain tau and tau comprising the paired helical filaments of Alzheimer′s disease.