FIGURE 4.

γ-Secretase complexes generate distinctive Aβ product profiles. A, Aβ products were measured using ELISA techniques and normalized to initial AICD generation. Results are plotted as % of the Aβ products generated by the PSEN1·APH1A γ-secretase complex (mean ± 95% CI, n = 12). Aβ₃₈ peptides were undetectable in reactions with the PSEN2·APH1B complex (ND). B, the sum of Aβ₃₈, Aβ₄₀, Aβ₄₂, and Aβ₄₃ was plotted as % of the PSEN1·APH1A complex (mean ± 95% CI, n = 12). Lower total Aβ levels suggest the accumulation of longer Aβ (>43) peptides. C, Aβ profiles analyzed in urea-based gels corroborate the accumulation of longer Aβ peptides by these complexes. Aβ₄₂ and Aβ₄₃ are running as one band, the asterisk denotes an aspecific band (between Aβ₄₀ and Aβ₃₈).