Folding and misfolding of the prion protein in the secretory pathway.

A hallmark of prion diseases in humans and animals is the conversion of the cellular prion protein PrPc to a pathogenic isoform, denoted PrPSc. PrPSc is characterized by distinct biochemical and biophysical properties; in addition, it is the major component of infectious prions. All available data indicate that the only difference between PrPc and PrPSc resides in their conformation, emphasizing a critical role of protein folding in the pathogenesis of prion diseases.