FIGURE 2.

Schematic overview of the current model for γ-secretase activity. APP-C99 is first cleaved by an endopeptidase activity to release the intracellular domain and a long Aβ peptide (Aβ₄₈ or Aβ₄₉). These longer Aβ peptides are then further processed by a consecutive carboxypeptidase-like activity at every third amino acid, except for the processing of Aβ₄₂ into Aβ₃₈, where four amino acids are released. Methods used for the detection and quantification of AICD and Aβ products are indicated.