Successful immunoisolation of DRM subfractions rich in APP or BACE1. Protein compositions of immunoisolated DRM subfractions were compared by silver staining (a) and WB (b). Brain-derived Lubrol DRMs were immunoaffinity purified with anti-APPc or anti-BACE1c. Protein band patterns of the DRM subfractions were distinct from that of the input (a). WB analysis showed minimal overlap between APP and BACE1 (b). X11, CASK, Munc18, and syntaxin 1 were enriched in APP DRMs. Proteins in the bound fraction derived from the same amount of DRM were loaded. The total amount of bound proteins in BACE1 DRMs estimated by SYPRO Ruby staining was roughly 50% of that in APP DRMs. PrP showed preferential association with APP DRMs over BACE1 DRMs.