Figure 3
Endogenous IDE co-localizes with flotillin-1 and Aβ on the plasma membrane. A- Brain rat membranes were processed as described in Materials and Methods and fractions analyzed by refractive index (□), distribution of total protein (○) and GPI-anchored alkaline phosphatase activity (◆). DRMs, fraction 3–4; DSMs, fractions 8–9. Fraction 1, top of the gradient; fraction 9, bottom of the gradient.B- Representative western blotting of the same amount of total protein from DRMs and DSMs isolated from cortical tissue of a FAD brain showed co-localization of IDE and flotilin-1 in DRMs. IF, intermediate fraction. C- Significant increased amount of Aβ 42 was detected in DRM compared to DSM by ELISA. Bars represent means ± S.E.M of 2 independent experiments. *p < 0.001. D- Immunogold electron microscopy on cryosections of N2aSW cells showed clusters of gold particles at the plasma membrane (panel 1). A higher magnification of the section framed in panel 1 (panel 2) clearly indicated co-localization of gold particles of different size corresponding to Aβ (white arrow, 15 nm) and IDE (black arrows, 6 nm). Scale bar, 50 nm.