Prions. David W. Colby 1 , * and Stanley B. Prusiner 1 , 2 + Author Affiliations stanley@ind.ucsf.edu Abstract The discovery of infectious proteins, denoted prions, was unexpected. PrP Sc , an alternative or abnormal isoform of PrP, stimulates the conversion of PrP C into nascent PrP Sc ; in the brain, accumulation of PrP Sc causes neurodegeneration. Figure 1. Prion protein isoforms. ( ) Western immunoblot of brain homogenates from uninfected (lanes 1 and 2) and prion-infected (lanes 3 and 4) Syrian hamsters. In the presence of detergent, PrP 27–30 polymerizes into amyloid ( McKinley et al. 1991 ).
As in mammals, proteins with self-propagating conformations have been found in fungi; these fungal prions share many similarities with mammalian prions ( Chien et al. 2004 ). THE PrP GENE A chromosomal gene encodes PrP and is denoted , which is a member of the gene family that also includes , encoding the doppel protein ( Moore et al. 1999 ), and , encoding shadoo ( Watts and Westaway 2007 ). Figure 2. Cellular Biology of Prion Diseases. Home.
TSEs in Humans. CJD Surveillance. Prions Abstract. Abstract Prions are unprecedented infectious pathogens that cause a group of invariably fatal neurodegenerative diseases by an entirely novel mechanism. Prion diseases may present as genetic, infectious, or sporadic disorders, all of which involve modification of the prion protein (PrP). Bovine spongiform encephalopathy (BSE), scrapie of sheep, and Creutzfeldt–Jakob disease (CJD) of humans are among the most notable prion diseases. Prions are transmissible particles that are devoid of nucleic acid and seem to be composed exclusively of a modified protein (PrPSc). The normal, cellular PrP (PrPC) is converted into PrPSc through a posttranslational process during which it acquires a high β-sheet content.
The species of a particular prion is encoded by the sequence of the chromosomal PrP gene of the mammals in which it last replicated.