Figure 5.

Model for Aβ-fragment release from the membrane. Mature APP is cleaved by β-secretase, releasing a soluble N-terminal fragment (APPsβ). The C-terminal fragment (CTF) is produced by ε-secretase cleavage together with Aβ 48–49 membrane-bound fragments. Longer Aβ fragments are further processed by ζ/γ-secretases, leaving Aβ 46 partly in the membrane while shorter, less hydrophobic fragments (Aβ 40–45) are released into the lumen of the ER.