FIG. 6.

Cholesterol accumulation alters membrane microdomain organization and impairs SNARE protein localization. A: SNAP-25, VAMP-2, syntaxin-1, and syntaxin-4 protein levels in isolated islets. Graphs represent pooled densitometric measurement of protein signal intensity from three separate experiments. Actin was used as the loading control. B: Representative Western blot of transferrin receptor (TfR), a marker for soluble fractions; flotillin, a marker for nonsoluble fractions; and SNAP-25 in lipid raft fractions of MIN6 cells treated with or without 2 mmol/L cholesterol (n = 2) for 30 min, followed by 10 mmol/L MβCD (n = 1) for an additional 30 min. Fractions 5–8 were designated as nonsoluble and band intensities quantified and expressed on the right panel. C: Representative Western blot of EGF-induced phosphorylation of AKT in isolated islets. Graphs represent pooled densitometric measurement of protein signal intensity from four separate experiments. **P < 0.01 compared with controls. (A high-quality color representation of this figure is available in the online issue.)