The study investigates the role of lipid rafts in the amyloidogenic processing of the Alzheimer's β-amyloid precursor protein (APP). Lipid rafts are cholesterol- and sphingolipid-enriched microdomains that play a crucial role in various cellular processes. The authors found that cholesterol depletion in N2a cells significantly reduced Aβ production, suggesting that lipid rafts are essential for Aβ generation. They demonstrated that APP and the β-site APP cleavage enzyme (BACE1) copatch at the plasma membrane upon cross-linking with antibodies and segregate away from nonraft markers. Cross-linking with antibodies increased Aβ production in a cholesterol-dependent manner. Endocytosis was essential for β-cleavage, and inhibition of endocytosis reduced Aβ secretion. However, this block could be overcome by cross-linking APP and BACE1. These findings indicate that lipid rafts are critical for regulating the access of α- and β-secretase to APP, thereby controlling Aβ generation. The study also suggests that APP partitions into two cellular pools: one associated with lipid rafts where Aβ is generated, and another outside rafts where α-cleavage occurs.The study investigates the role of lipid rafts in the amyloidogenic processing of the Alzheimer's β-amyloid precursor protein (APP). Lipid rafts are cholesterol- and sphingolipid-enriched microdomains that play a crucial role in various cellular processes. The authors found that cholesterol depletion in N2a cells significantly reduced Aβ production, suggesting that lipid rafts are essential for Aβ generation. They demonstrated that APP and the β-site APP cleavage enzyme (BACE1) copatch at the plasma membrane upon cross-linking with antibodies and segregate away from nonraft markers. Cross-linking with antibodies increased Aβ production in a cholesterol-dependent manner. Endocytosis was essential for β-cleavage, and inhibition of endocytosis reduced Aβ secretion. However, this block could be overcome by cross-linking APP and BACE1. These findings indicate that lipid rafts are critical for regulating the access of α- and β-secretase to APP, thereby controlling Aβ generation. The study also suggests that APP partitions into two cellular pools: one associated with lipid rafts where Aβ is generated, and another outside rafts where α-cleavage occurs.