PRNP and scrapie: The mechanism by which the cellular PrP (PrPC) is converted into the pathogenic scrapie‐type PrP (PrPSc) appears to involve a post‐translational change in PrPC conformation, from a predominantly α‐helical into a predominantly β‐sheet structure.1 PrPSc is the major, if not the sole, component of the transmissible agent in prion diseases.