Figure 1. Schematic drawing of the generation of β-amyloid (Aβ) from its precursor, amyloid precursor protein (APP). APP is a transmembrane protein with a large extracellular N-terminal domain and a smaller intracellular tail. The Aβ domain is partly embedded in the plasma membrane. In the amyloidogenic pathway, APP is first cleaved by β-secretase, resulting in the release of β-secretase-cleaved soluble APP (β-sAPP). In the second step, the 99-amino acid C-terminal fragment (CTF, C99) of APP is cleaved by the γ-secretase-complex-releasing free Aβ. KPI, Kunitz protease inhibitor; 0X2, 0X2 antigen.
