Figure 3. Schematic of the interactions between γ-secretase, its substrate APP and DAPT.

The catalytic hydrolysis of APP is controlled by the number of molecules interacting with γ-secretase. Secondary binding of APP or DAPT increases the potential hydrolytic rate dramatically. However, interactions of a third APP or DAPT molecule shuts γ-secretase off suggesting the enzyme may become clogged or be highly regulated catalytically.