Fig. 5.
Downregulation of classical, but not atypical, PKC isozymes by phorbol esters. The distribution of protein kinase C isoforms was analyzed by immunoblots after a 24 hr treatment of cultures with 100 μmAA, with 1 μm of the inactive and active phorbol esters αPDBU and βPBDU, respectively, or with the vehicle 0.1% DMSO. Cells were lysed as described in Materials and Methods; aliquots of the pellet and supernatant corresponding to 2 × 105 cells were applied to SDS-polyacrylamide gels. Nitrocellulose blots were probed with peptide antisera specific for PKCα (A), PKCε (B), and PKCζ (C). Arrows indicate the position of bands that were blocked when antibodies had been preincubated with the corresponding immunogenic peptide (not shown). Data are representative of three additional experiments performed on different preparations.