Fig. 3. Coprecipitation of GST-MegBP and megalin from mouse renal extracts. Mouse renal membrane extracts were incubated with anti-glutathione IgG in the presence (lane 2) or absence of GST-MegBP (lane 3). Proteins bound to IgG were recovered as detailed in the Materials and Methods section and subjected to non-reducing 4-12% SDS-PAGE and immunoblot analysis using a goat anti-megalin antibody and enhanced chemoluminescence. As a positive control, 2 µg of renal membrane preparations were run in parallel (lane 1). Endogenous mouse megalin was recovered in the presence but not in the absence of GST-MegBP. The arrow indicates full-length megalin. The lower molecular weight band corresponds to a megalin degradation product often observed in membrane preparations.