Fig. 3.

Immunoblot profiles of PK-resistant PrP^Sc fragments (PrP^res) in the reported sCJD cases. A Immunoblot analysis of PK-treated frontal cortex homogenates by standard SDS-PAGE gel electrophoresis (running gel of 6.5 cm). The six reported cases (#1–6) are compared with sCJD cases of the MM1, MV1, VV1, and VV2 groups. Note the slightly faster migration of unglycosylated PrP^res in cases 1–6 and the VV1 compared to the MM1 and MV1. B Immunoblot analysis of PK-treated frontal cortex homogenates by high-resolution SDS-PAGE gel electrophoresis (running gel of 15 cm). A sCJD MM1 and a sCJD VV1 are included for comparison with cases #1–4. The higher resolution of the gel shows that unglycosylated PrP^res in VM1 and VV1 cases comprises a doublet (i.e., two bands of 21 and 20 kDa), explaining the slightly faster migration compared to MM1 and MV1 cases (they show one band of 21 kDa) C Immunoblot profile of PrP^res comprising PrP^Sc type 1 and the 12–13 kDa C-terminal fragments. Note the higher proportion (i.e., relative amount) of C-terminal fragments in VM1 and VV1 cases compared to MM1 and MV1 (see Table 3 for the quantitative data). D Comparison of the electrophoretic mobility of PK-resistant PrP^Sc after digestion at pH 6.9 or 8.0 (see * labels). There is a more consistent shift in migration (i.e., faster) when PK digestion is performed at pH 8 in MM1 and MV1 cases compared to VM1 and VV1. The immunoblots shown in A, B, and C are labeled by the N-terminal mAb 3F4. In contrast, the immunoblot in panel C is stained with the C-terminal antiserum 2301. Approximate molecular masses are in kilodaltons