Figure 1.

Formation of protease-resistant ³⁵S-PrP by ³⁵S-PrP-sen with homologous and heterologous PrP-res under Gdn⋅HCl-free conditions. (A) The species of PrP-sen and PrP-res are indicated above the figure as H (hamster), M [mouse PrP-res or mouse(3F4)-PrP-sen]. Controls lacking PrP-res are indicated by −. −PK and +PK indicate PK-untreated and PK-treated samples, respectively. The major band of the ³⁵S-PrP-sen (lacking the glycosyl-phosphatidylinosital anchor) was unglycosylated and comigrated with the 28.5-kDa marker. The protease-resistant ³⁵S-PrP bands quantified by PhosphorImager analyses are indicated by the bracket on the right side. The bands lying below the bracket are partial conversion products, the formation of which appears to be less species dependent in this and previous studies (7). Molecular mass markers are on the left (in kDa). (B) Quantitation of the formation of protease-resistant ³⁵S-PrP. The means and standard deviations of five independent experiments are indicated. Statistical significance of the differences between the means is designated by ** and *** for P < 0.01 and P < 0.001, respectively, in an unpaired t test. −, Without PrP-res.