NR ACJZ
AU Caughey,B.W.; Raymond,G.J.; Ernst,D.; Race,R.E.
TI N-terminal truncation of the scrapie-associated form of PrP by lysosomal protease(s): implications regarding the site of conversion of PrP to the protease-resistant state.
QU Journal of Virology 1991 Dec; 65(12): 6597-603
PT journal article
AB Scrapie and related transmissible spongiform encephalopathies result in the accumulation of a protease-resistant form of an endogenous brain protein called PrP. As an approach to understanding the scrapie-associated modification of PrP, we have studied the processing and sedimentation properties of protease-resistant PrP (PrPres) in scrapie-infected mouse neuroblastoma cells. Like brain-derived PrPres, the neuroblastoma cell PrPres aggregated in detergent lysates, providing evidence that the tendency to aggregate is an intrinsic property of PrPres and not merely a secondary consequence of degenerative brain pathology. The PrPres species had lower apparent molecular masses than the normal, protease-sensitive PrP species and were not affected by moderate treatments with proteinase K. This suggested that the PrPres species were partially proteolyzed by the neuroblastoma cells. Immunoblot analysis of PrPres with a panel of monospecific anti-PrP peptide sera confirmed that the PrPres species were quantitatively truncated at the N terminus. The metabolic labeling of PrPres in serum-free medium did not prevent the proteolysis of PrPres, showing that the protease(s) involved was cellular rather than serum-derived. The PrPres truncation was inhibited in intact cells by leupeptin and NH4Cl. This provided evidence that a lysosomal protease(s) was involved, and therefore, that PrPres was translocated to lysosomes. When considered with other studies, these results imply that the conversion of PrP to the protease-resistant state occurs in the plasma membrane or along an endocytic pathway before PrPres is exposed to endosomal and lysosomal proteases.
IN In von Scrapie oder anderen infektiösen spongiformen Encephalopathien befallenen Gehirnzellen aggregiert eine durch zelluläre, vermutlich lysosomale Proteasen am N-Terminus verkürzte, proteaseresistente Form des endogenen Gehirnproteins PrP. In intakten Zellen wird diese Verkürzung des PrP durch Leupeptin und NH4Cl inhibiert.
MH Animal; Cell Aggregation; Cell Line; Electrophoresis, Polyacrylamide Gel; Endopeptidases/isolation & purification/*metabolism; Lysosomes/*enzymology; Mice; Neuroblastoma; PrPsc Proteins; Prions/*genetics/metabolism; *Protein Processing, Post-Translational
AD Laboratory of Persistent Viral Diseases, National Institute of Allergy and Infectious Diseases, Hamilton, Montana 59840.
SP englisch
PO USA