Western blotting of homogenates from scrapie positive tonsil and retropharyngeal lymph node. Tonsillar (lanes 1, 3) and medial retropharyngeal lymph node (lanes 2, 4) material digested with proteinase K was analyzed by WB and developed with monoclonal antibody P4 (0.2 μg/ml). Enzymatic treatment with PNGaseF is indicated. Lanes 1–4: Applied amounts 450 μg TE/lane. Lane 5: molecular weight markers. Position of markers are in kDa. Other symbols: open arrowhead for top of gel, bold arrowhead for front of bromphenol blue, bracket for migration position of PrPres triplet, small lines for the three individual PrPres polypeptides in the triplet as discussed in the Results section. Position of markers is in kDa. Band at 14 kDa represents lysozyme from SeeBlue Mark12 which is bound by anti-mouse alkaline phosphatase conjugate.