The human cellular prion protein (PrPC) is a glycosylphosphatidylinositol- (GPI-) anchored membrane glycoprotein, and a conformationally altered β-structure-rich insoluble isoform of PrPSc, scrapie, is an infectious agent responsible for transmissible spongiform encephalopathies, which affect both humans and animals. This evidence concerns the gene PRNP and scrapie.