ApoER2 interacts with APP in N2a cells. (A), co-immunoprecipitation of ApoER2 with APP. Cell extracts were prepared from ApoER2-expressing cells transiently transfected with APP695-Myc. Extracts were immunoprecipitated with anti-Myc or with the unrelated, anti-V5 antibody and probed for ApoER2 and APP with the anti-HA and anti-Myc antibodies, respectively. L, input lysate. NB, not bound. (B), cell extracts were prepared from untransfected ApoER2-expressing cells and processed as in A. anti-Myc antibody does not immunoprecipitate ApoER2 by itself. Middle panel, anti-Myc antibody do immunoprecipitate APP695Myc in single transfected cells. Lower panel, anti-V5 antibody immunoprecipitation idoneity was confirmed by β-catenin-V5 precipitation from transfected N2a cells. (C), independent lysates from ApoER2-expressing cells and from APP695-Myc-transfected cells were combined and the co-immunoprecipitation experiment was continued with the anti-Myc antibody as in A. ApoER2-HA and APP695-Myc requires an in vivo context for interaction. Remnants of ApoER2 detection after stripping and reblot are indicated by an asterisk.