Immunoprecipitation of A
and p3 from wild-type and mutated PS1-expressing HK293 cells
Stable transfectants overexpressing PS1 or the indicated mutated PS1 were transiently transfected with 2 µg of wild-type βAPP751. Two days after transfection, cells were metabolically labeled for 6 hr; then conditioned media were submitted to a two-step immunoprecipitation by FCA3340 and FCA3542 (350-fold dilution). Immunoprecipitated proteins were electrophoresed on a 16.5% Tris-tricine gel, radioau-tographed, and scanned as described in Materials and Methods. Panel A illustrates the ratio of Aβ42 over total Aβ (Aβ42 + Aβ40) and panel B indicates the ratio of p342 over total p3 (p342 + p340) observed with the indicated independent numbered clones. Values are the means ± S.E.M of three determinations.