Skip to main content
. 1997 Apr 15;94(8):4125–4130. doi: 10.1073/pnas.94.8.4125

Figure 4.

Figure 4

Effect of APP clinical mutants on the production of βA4 and its C-terminal variants β40 and β42. (A) Detection of APPsec, holoAPP, total βA4, β40, and β42 in hippocampal neurons expressing APPwt, APPLond, and APPSwe. APPsec and APPFL are shown on the top, and the lanes numbered as 1 represent total βA4. The lanes numbered 2 represent β40, and those numbered 3 represent β42. (B) Total βA4 in the medium (filled) and cell lysates (hatched) after normalizing to holoAPP levels in neurons expressing APPwt, APPLond, and APPSwe (n = 8 each). Quantification was based on pair-wise comparisons between APPwt and the clinical mutants within each experiment. The levels of secreted and intracellular βA4 from APPwt are fixed to 1 and 0.15, respectively, which reflects the mean ratio between these two pools of βA4. (C) Comparison of 42/40 ratios between APPwt and the clinical mutants. The 42/40 ratio in the medium and cell lysates were analyzed separately; both are fixed at 1 in APPwt which is used as a reference (shown by the dashed line). APPLond vs. APPwt, P < 0.02 (medium) and P < 0.02 (cells); APPSwe vs. APPwt, P = not significant (medium) and P < 0.05 (cells); APPLond vs. APPSwe, P < 0.05 (medium) and P < 0.002 (cells). Student’s t test was used for pair-wise comparisons within each set of experiments (n = 9). APPLond vs. APPwt 1-tailed P values, other comparisons 2-tailed. (D) β42 levels in APPwt and the clinical mutants after normalizing to holoAPP. Medium and cell lysates were analyzed separately, and both are fixed to 1 in APPwt. APPLond vs. APPwt, P < 0.02 (medium) and P < 0.02 (cells); APPSwe vs. APPwt, P < 0.001 (medium) and P < 0.01 (cells); APPLond vs. APPSwe, P = not significant. Student’s t test for pair-wise comparisons (n = 8 each). (E) The 42/40 ratios in cells vs. medium of neurons expressing APPwt, APPLond, and APPSwe. The 42/40 ratio in the medium of each dish is fixed to 1. Cells vs. medium difference was analyzed by Student’s t test for pair-wise comparisons (n = 9 each): APPwt, P < 0.001; APPLond, P < 0.02; APPSwe, P = not significant (2-tailed P values).