Immunoblot showing that anti-PP-2A recognizes a 36-kD protein. Aliquots of a K562 cell lysate (lane 1) or a solubilized K562 cell membrane preparation (lane 2) were applied to 7.5% SDS polyacrylamide gels along with samples of low-ionic strength, antiphosphotyrosine (RC20) immunoprecipitates (lane 3) and samples of the immunoprecipitate obtained in the presence of 200 nmol/L rapamycin (lane 4). After development of these gels, proteins were blotted onto polyvinylidene difluoride (PVDF) membranes and blots were overlaid with (1 to 5,000) monoclonal anti-PP-2Ac (clone 46, IgG1). Second antibody was (1 to 5,000) goat antimouse IgG conjugated with horseradish peroxidase and detection was by enhanced chemiluminescence (ECL). The 42-kD molecular mass marker is shown on the left.
