Figure 2. Aβ aggregation: role of apoE.

During the Aβ aggregation process, Aβ monomers change their conformation to a β-sheet-rich structure and form soluble oligomers or insoluble intermediate aggregates. Such nuclei further accelerate the fibrillogenesis to form large insoluble fibrils as “seeds” (Harper and Lansbury, 1997). The association of apoE with an Aβ nucleus is likely to block its seeding effect which accelerates Aβ fibrillogenesis. Under certain conditions, apoE and Aβ may form large co-aggregates. Newly generated Aβ fibrils can bind to existing aggregates, resulting in the formation of even larger co-aggregates, with or without additional apoE (Wood et al., 1996a). Finally, these aggregates may deposit as amyloid plaques in the brain.