Fig. 2

Validation of Probe-dependent Proximity Profiling (ProPPr) method. A Schematic representation of the ProPPr method. B Western blotting of the tissue lysates reveals extensive biotinylation in the AD samples treated by ProPPr method, but not in the negative controls where staining with AT8 antibodies was omitted. I – input lysate; F – flow-through after pulldown with streptavidin beads. Silver staining of the proteins eluted from streptavidin beads after pulldown revealed increased level of protein in the ProPPr samples comparing to negative controls where staining with AT8 antibodies was omitted. AT8 ProPPr quality control images compared distribution, tau burden by digital pathology and NeutrAvidin-488 labeling of AD frontal cortex. C-F Representative images of routine AT8 IHC with and fluorescent neutravidin labeling of proximity biotinylated proteins with AT8 ProPPr in adjacent sections from AD (C), PiD (D), CBD (E), and PSP (F) cases. Staining patterns on adjacent sections are evenly matched between the IHC and proximity-biotinylation of phospho-tau in macroscopic cortical tile images and high magnification microscopy demonstrates the specific labeling of tau lesions found in each tauopathy. Created with BioRender.com