Amyloid precursor protein (APP) is  a type I integral membrane protein ubiquitously expressed in many tissues and concentrated in the synapses of neurons. The majority of APP is cleaved at the plasma membrane by the α-secretase in the non-amyloidogenic pathway.  The amyloidogenic pathway starts with β-secretase cleavage by BACE1 on the N-terminal part of the Aβ domain, releasing sAPPβ from a membrane-anchored fragment named βCTF or C103, which is subsequently cleaved by γ-secretase to release Aβ.