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Abstract
According to the amyloid pore hypothesis, pores formed by small oligomers of misfolded amyloidogenic proteins cause membrane leakage with the unregulated rapid influx of ions leading to cell death. Ultrastructurally, pores reconstituted in vitro have mainly been characterised so far, and the presence of in situ pores in the amyloid tissues has not yet been demonstrated. In this study, the presence of in situβ amyloid (Aβ) pores was shown with high resolution transmission electron microscopy, in the neuronal cell membrane as well as in the membrane of mitochondria-like organelles in the brain with Alzheimer's disease. They are 16 nm wide and 11 nm long flat columnar structures made up of a single cylindrical layer (wall) of laterally associated Aβ protofilaments which surrounds a 10 nm wide opening or lumen. Protofilaments are the basic unit of the fibrils of all amyloid-forming proteins and peptides. Individual extracellular Aβ protofilaments were 2–3 nm wide straight tubular structures with helical wall formed by the tight coiling of 1 nm wide Aβ filaments. These in situ Aβ pores are similar but not identical to in vitro reconstituted Aβ pores.
| Abbreviations | ||
| AD | = | Alzheimer's disease |
| Aβ | = | β amyloid |
| CSPG | = | chondroitin sulphate proteoglycan |
| TEM | = | transmission electron microscopy |
| AFM | = | atomic force microscopy |
| Abbreviations | ||
| AD | = | Alzheimer's disease |
| Aβ | = | β amyloid |
| CSPG | = | chondroitin sulphate proteoglycan |
| TEM | = | transmission electron microscopy |
| AFM | = | atomic force microscopy |