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. Author manuscript; available in PMC: 2012 May 1.
Published in final edited form as: J Neurochem. 2011 Mar 15;117(3):359–374. doi: 10.1111/j.1471-4159.2011.07213.x

Figure 1. Pathways of APP proteolysis.

Figure 1

The full-length APP is a type-I integral membrane protein. It is cleaved in the exocytoplasmic domain at the start of Aβ by β-secretase and between residues 16-17 of Aβ by α secretase to generate secreted derivatives sAPPβ and sAPPα and C-terminal fragments CTFβ and CTFα. γ-Secretase cleaves CTFβ at the membrane cytoplasm boundary (ε site) to CTFγ and Aβ49, and subsequently to Aβ40 and Aβ42. Most secreted Aβ ends at residue 40 but a small percentage is longer terminating at residues 42 and 43. CTFα is similarly processed by γ-secretase (not shown). The predicted CTFγ is not seen probably due to its rapid turnover in the cell.