The major polypeptide of scrapie-associated fibrils (SAF) has the same size, charge distribution and N-terminal protein sequence as predicted for the normal brain protein (PrP)

EMBO J. 1986 Oct;5(10):2591-7.


Scrapie-associated fibrils (SAF) are unique structures characteristic of the group of unconventional slow infections which includes scrapie and Creutzfeldt-Jakob disease. A major component of hamster fibrils has been described as a protease-resistant glycoprotein with an apparent mol. wt of 27,000-30,000 (PrP27-30). However, we report here that if fibrils are prepared by procedures designed to minimise proteolysis the PrP proteins co-purifying with hamster SAF have mol. wts of 33,000-35,000 (PrP33-35) and 26,000-29,000 (PrP26-29). We find a Lys-Lys-Arg-Pro-Lys sequence at the amino terminus of these SAF proteins, that is absent from PrP27-30, and which has recently been predicted to be the N-terminal sequence of the native PrP protein of uninfected brain. The major SAF protein (PrP33-35) and its normal brain homologue are shown to have the same apparent mol. wt and ionic charge distribution by two-dimensional gel analysis, silver staining and immunoblotting. These results support our view that PrP33-35 and the normal brain PrP protein may have the same covalent structure, and that the PrP protein is recruited into these amyloid-like SAF or into association with a non-protein component of SAF by an irreversible event initiated directly or indirectly by scrapie infection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Brain / microbiology*
  • Brain Chemistry*
  • Chromatography, Gel / methods
  • Cricetinae
  • Electrophoresis, Polyacrylamide Gel / methods
  • Nerve Tissue Proteins / isolation & purification*
  • Prions / analysis*
  • Viral Proteins / isolation & purification*


  • Nerve Tissue Proteins
  • Prions
  • Viral Proteins