Figure 1.

A diagram of amyloid precursor protein (APP) processing pathway. The transmembrane protein APP (membrane indicated in blue) can be processed by two pathways: the nonamyloidogenic α-secretase pathway and the amyloidogenic β-secretase pathway. In the nonamyloidogenic pathway, α-secretase cleaves in the middle of the β-amyloid (Aβ) region (red) to release the soluble APP-fragment sAPP-α. The APP C-terminal fragment 83 (APP-CTF83, αCTF) is then cleaved by γ-secretase to release the APP intracellular domain (AICD) and P3 fragment. In the amyloidogenic pathway, β-secretase cleaves APP to produce the soluble fragment sAPP-β. APP-CTF99 (βCTF) is then cleaved by γ-secretase to produce Aβ ₄₀, Aβ ₄₂, and AICD. Adopted from [179].