Figure 2.

Defining the N-terminal minimum boundary for γ-secretase cleavage. Defining the N-termini of the minimum substrate by the γ-secretase Epsilon-Cleavage assay based on C99 (A) and Aβ₅₉ (B) hybrid proteins. Cartoon illustration of N-terminal C99 truncations (left side) and their cleavage efficiencies (right side). The numbers in the cartoon illustration indicate the first residue in each construct. The inlet panels show relative protein expression of some critical boundary constructs, with corresponding construct numbers marked on top of each lane. Aβ peptide (E22-K55) is the minimum substrate of γ-secretase that retains a close to normal cleavage level. Error bars=SEM, n=3, P-values (two-tailed Student's t-test versus WT): ^*P<0.05; ^**P<0.01, ^***P<0.001.