Fig. 1.
Schematic illustration demonstrating similarities in the relationships between the PrPC protein and prion diseases, and the α-synuclein protein and Parkinson's disease. (A) The cellular prion protein (PrPC) comprises ≈210 aa. The function of PrPC is unknown. PrPC has a largely α-helical conformation and resides on the surface of cell membranes. When PrPC misfolds, it acquires a high β-sheet content and assembles into rods that coalesce to form amyloid plaques. PrPSc is the sole component of the infectious prion and can lead to disease in animals and humans (19). (B) α-Synuclein is a protein of ≈140 aa. The function of α-synuclein is unknown. α-Synuclein acquires a largely α-helical conformation when it binds to cell membranes. When α-synuclein misfolds, it acquires a high β-sheet content and polymerizes into fibrils that are associated with the formation of Lewy bodies. Overexpression of α-synuclein alone can induce a PD syndrome in animals and humans.