Pronase E-resistant RML prion infectivity is precipitated by NaPTA.

<p>10% (w/v) homogenates from normal CD-1 brain (CD-1, white bars) or RML prion-infected brain (RML, black bars) were either untreated (whole homogenate), incubated at 37°C for 90 min and 20°C for 30 min (temperature control), digested with pronase E at 100 µg/ml, 37°C for 30 min (pronase), precipitated by NaPTA (NaPTA) or sequentially digested by pronase E at 100 µg/ml, 37°C for 30 min and precipitated by NaPTA (pronase + NaPTA). The concentration of PrP in all samples was measured by ELISA (A) and is expressed as a percentage of the total PrP present in the untreated RML samples; mean ± S.E.M. (<i>n</i> = 5). RML prion infectivity was measured by the Scrapie Cell Assay (B) and expressed as total infectivity present in the samples; mean ± S.E.M. (<i>n</i> = 5).