Figure 2.

Possible roles of the N-terminal regions in the conversion of PrP^C into PrP^Sc. Upon conversion of PrP^C into PrP^Sc, PrP^C might interact with PrP^Sc through glycosaminoglycans (A) or through the polybasic and OR regions (B). (C) The polybasic and OR regions are also involved in endocytosis of PrP^C to endosomal compartments, where PrP^C is considered to convert into PrP^Sc. Extra OR sequences in the OR region (D) and point mutations in the post-OR region (E) might render mutated PrPs structurally unstable, ultimately leading to their spontaneous conversion to pathogenic PrPs.