Figure 6. γ-Secretase preferentially cleaves APP near the helix-destabilizing Gly-Gly motif.

(A) Aβ38 levels from HEK cells transiently transfected with V39F, V40F, I41F or A42F APP. Aβ levels measured by 4G8 ELISA. Mean ± SD, n = 3. (B) Aβ42/40 ratios from V44F-I47F-V50F and I45F-T48F-M51F triple mutants from transiently transfected HEK cells. Aβ levels measured by 4G8 ELISA. Mean ± SD, n = 3, t-test, ****<0.0001. (C) Aβ38, Aβ40 and Aβ42 levels from HEK cells transfected with V44F-I47F-V50F and I45F-T48F-M51F triple mutants, the V44F-I45F double mutant and the hexa-mutant V44F-I45F-I47F-T48F-V50F-M51F. Aβ levels measured by 4G8 ELISA. Mean ± SD, n = 3. (D) Schematic diagram of sequential Phe mutants in the TMD of APP. (E) Aβ38 + 40 + 42 secreted from HEK cells transiently transfected with the mutants from (D). Aβ levels measured by 4G8 ELISA. Mean ± SD, n = 3, t-test ***<0.001, ****<0.0001. (F) Aβ42/40 ratios from (E). Aβ levels measured by 4G8 ELISA. Mean ± SD, n = 3, t-test *<0.05, ****<0.0001.

DOI: http://dx.doi.org/10.7554/eLife.17578.009

Figure 6—figure supplement 1. HEK cell expression and Aβ production from consecutive phenylalanine APP mutants.

(A) Aβ38, Aβ40 and Aβ42 levels secreted from HEK cells after transient transfection with APP mutants containing stretches of consecutive phenylalanines (see Figure 6D). Aβ levels measured by 4G8 ELISA. Mean ± SD, n = 3. (B) Expression levels of consecutive phenylalanine APP mutants from Figure 6D.

DOI: http://dx.doi.org/10.7554/eLife.17578.010