Purification and partial characterization of the normal cellular homologue of the scrapie agent protein.
The scrapie agent protein (Sp33-37) is a degradation-resistant protein that aggregates into fibrils and amyloid plaques. This protein is derived from a normal cellular protein (Cp33-37). Understanding the mechanism responsible for the conversion of Cp33-37 to Sp33-37 may explain scrapie agent replication. Cp33-37 was extracted from normal hamster brain and purified 2700-fold by an immunoaffinity method. Both Cp33-37 purified from normal hamster brain and Sp33-37 purified from scrapie-affected hamster brain had apparent masses of 33-37 kilodaltons and displayed microheterogeneity characteristic of glycoproteins. Cp33-37 was completely digested by proteinase K under conditions that resulted in conversion of Sp33-37 to the protease-resistant fragment PrP27-30. Cp33-37 did not cause scrapie when inoculated intracerebrally into hamsters. Fractions containing purified Sp33-37 had average titers of greater than 10(11) LD50 of the scrapie agent/mg of protein; these titers were not diminished by proteinase K. These results indicate that altered sensitivity to proteolysis in vitro reflects an intrinsic difference between Sp33-37 and Cp33-37.
Bendheim
P E
PE
Department of Pathological Neurobiology, New York State Institute for Basic Research in Developmental Disabilities, Staten Island.
Potempska
A
A
Kascsak
R J
RJ
Bolton
D C
DC
D000818:Animals; D001923:Brain Chemistry; D002458:Cell Fractionation; D002499:Centrifugation, Density Gradient; D002846:Chromatography, Affinity; D006224:Cricetinae; D005260:Female; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000302:isolation & purification*; D018622:PrP 27-30 Protein; D011498:Protein Precursors / Q000032:analysis / Q000302:isolation & purification*; D012608:Scrapie / Q000209:etiology*
D009419:Nerve Tissue Proteins; D011498:Protein Precursors; D018622:PrP 27-30 Protein