Prion protein is strongly immunolocalized at the postsynaptic domain of human normal neuromuscular junctions

Using three well-characterized polyclonal and monoclonal antibodies against prion protein (PrP), we demonstrated a strong concentration of PrP at human neuromuscular junctions (NMJs). Applying double and triple fluorescence-labeling, we found that PrP immunoreactivity exactly co-localized with alpha-bungarotoxin (alpha-BT) identified acetylcholine receptors, as well as with the high junctional concentrations of beta-amyloid precursor protein, beta-amyloid protein, desmin, ubiquitin and dystrophin. Therefore, PrP was considered to be located on the postsynaptic muscle membrane. At all NMJs identified by bound alpha-BT, strong PrP immunoreactivity was obtained with all PrP antibodies. This appears to be the first demonstration of PrP concentrated at human NMJs.