The membrane location of scrapie infectivity.

Using 5'-nucleotidase and NADPH: cytochrome c reductase as respective enzyme markers for the plasma membrane and endoplasmic reticulum, a satisfactory separation of these two membrane fractions from a cell line (SMB) derived from a scrapie mouse brain has been achieved. The coincident distribution of scrapie infectivity and 5'-nucleotidase in various fractions isolated from these cells indicates that most of the scrapie infectivity present in this cell line is associated with the plasma membrane.