PrP^C directly interacts with sortilin on the cell surface and inside cells.

<p>(A, B) Co-immunoprecipitation assay in N2aC24 cells with SAF61 anti-PrP Ab (A) or rabbit polyclonal anti-sortilin Abs (B). Arrows and arrowheads indicate a non-specific signal of the degraded fragment of protein G or the light chain of antibodies used in co-immunoprecipitation. Percentages indicate the proportion of the sample loaded. (C) GST-pulldown assay using GST-tagged VPS10P domain of sortilin and His-tagged full-length recombinant PrP or His-tagged recombinant PrP lacking residues 23–88. Percentages indicate the proportion of the sample loaded. (D) Co-immunoprecipitation assay in mouse brain homogenate with SAF61 anti-PrP Ab. Percentages indicate the proportion of the sample loaded. Arrowheads indicate a non-specific signal of the degraded fragment of protein G. (E) Double immunofluorescence staining of PrP^C (green) and sortilin (red) in permeabilized or non-permeabilized N2aC24 cells, with SAF83 anti-PrP Ab and goat polyclonal anti-sortilin Abs. Arrowheads indicate co-localized signals of PrP^C and sortilin. Bar, 5 μm. (F) Person’s correlation coefficient for cell surface and intracellular co-localization of PrP^C and sortilin.