Fig. 5
Phosphorylation of Thr654 and Ser655 of APP in cultured cell lines
APP was immunoprecipitated from (a) PC12, or (b) CHO cell lysates using the G-369 antibody. Samples were subjected to SDS-PAGE and immunoblotting as described above. Membrane strips were probed with either G-369, pAbS655, or pAbT654 antibodies. (a) The arrows indicate the positions of the three immature and three mature APP isoforms found in PC12 cells (see text for discussion). In the experiment shown, lanes 2 and 3 were exposed five times longer than lane 1. (b) CHO cells were stably transfected with a cDNA construct encoding APP751. The arrows indicate the positions of immature and mature isoforms of APP751. For all conditions studied, immunoreactivity detected by phosphorylation state-specific antibodies in all cell lines was competed away when each antibody was preincubated with the corresponding phospho-peptide antigen (10 µM) (data not shown).