A8 Prions

Prions ‘Prion’ is a term originally derived from ‘proteinaceous infectious particles’. Prions are believed to be composed entirely of protein. A normal host cellular gene encodes the prion protein, which exists as a cellular isoform, PrP^C, of Mr 33–35kDa, and as an abnormal isoform, PrP^Res PrP^C is completely digestible by proteinase K but PrP^Res is digested only as far as a 27–30kDa product. PrP 27–30 therefore accumulates in tissues containing PrP^Res.