The lipid raft is shown as part of the plasma membrane. The phospholipid domain (light blue) is separate from the lipid raft. The latter is enriched in glycosphingolipids and sphingomyelin (red) on the exofacial leaflet and glycerolipids (e.g., phosphatidylserine and phosphatidylethanolamine; green) on the cytofacial leaflet. Cholesterol (black) is enriched in both leaflets. The acyl chains in lipid rafts are more able to pack together. APP (Aβ region in maroon) is localized in raft and non-raft fractions, but predominates outside rafts. The α-secretase is not raft-associated, while the βand γ-secretases predominate in rafts. The cell surface is shown for clarity, although β-cleavage predominantly occurs in endosomes.