FIGURE 5.

γ-Secretase processing of different substrates by PS1 TM2 variants. A, stable PS1^−/−/PS2^−/− MEF pools expressing PS1 TM2 variants were transiently infected with APP_Swe retrovirus. The cell lysates were analyzed by immunoblotting with antibody CTM1. The levels of secreted Aβ₄₀ peptides in the conditioned media were quantified by ELISA. B, stable PS1^−/−/PS2^−/− MEF pools expressing PS1 TM2 variants were transiently infected with a retrovirus expressing APP C99–6Myc (top panel) or NotchΔEMV-6myc (middle panel). The lysates were analyzed by immunoblotting with mAb 9E10. The blots were reprobed with N-cadherin antibody (bottom panel). C, co-immunoprecipitation (co-IP) of γ-secretase and substrates. Stable PS1^−/−/PS2^−/− MEF pools expressing PS1 TM2 variants were transiently infected with retrovirus expressing APP_Swe or NotchΔEMV-6myc. The lysates were analyzed by co-immunoprecipitation with PS1_NT antibody and immunoblotted with APP, 9E10, or N-cadherin antibodies.