FIGURE 4.

Localization of APP and APP CTFβ into DRM in the cortex of wild-type, X11-deficient, X11L-deficient, and X11/X11L doubly deficient mice. A, isolation of DRM of cortex. Post-nuclear supernatant from the wild-type and the deficient mouse (8–12 weeks) brain cortex was fractionated by sucrose density gradient centrifugation. Each fraction was subjected to immunoblot analysis with anti-calnexin (non-DRM marker) and anti-flotillin-1 (DRM marker) antibodies. B and C, proteins in DRM and non-DRM fractions. DRM (B; fraction 4 in A) and non-DRM (C; fraction 9 in panel A) samples (40 μg of proteins) were probed with anti-APP (Sigma product), anti-BACE-Cat1, and anti-PS1-C antibodies. The densities of protein bands were standardized to the density of flotillin-1 for DRM (B) and calnexin for non-DRM (C), which was compared with the ratios for wild-type mice, which were assigned a reference value of 1.0 (values represent the means ± S.E.). The data were analyzed by a one-way analysis of variance followed by the Tukey's test (n = 4; ^*, p < 0.05; ^**, p < 0.01). mAPP, mature APP species (N- and O-glycosylated APP695 isoforms); imAPP, immature APP (N-glycosylated APP695 isoform).