Translocation of protein kinase C is not required to inhibit the antigen-induced increase of cytosolic calcium in a mast cell line.
Cross-linking of receptor bound IgE antibodies by multivalent antigen (DNP8-BSA) on PB-3c cells leads to an increase of cytosolic calcium ((Ca2+)i). Active tumor promoting phorbol esters and teleocidin which specifically activate the phospholipid Ca2+-sensitive protein kinase (PKC), inhibited the antigen-mediated rise in (Ca2+)i and induced a time and dose-dependent translocation of cytosolic PKC to membranes of the PB-3c cells as determined by enzyme activity or immunoblotting using a polyclonal anti-PKC antibody. This TPA concentration did not affect the subcellular distribution of PKC, although 1 nM of 12-O-tetradecanoylphorbol-13-acetate (TPA) inhibited to 50% the antigen-mediated increase in (Ca2+)i. The concentration of TPA required to induce a half-maximal subcellular redistribution of immunodetectable PKC activity was an order of magnitude greater than the half-maximal dose required to inhibit the antigen-mediated increase in (Ca2+)i. These data demonstrate that the TPA-dependent activation of PKC is not directly coupled to its translocation to membranes.
D000936:Antigen-Antibody Complex; D000941:Antigens / Q000276:immunology*; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D003600:Cytosol / Q000378:metabolism; D007073:Immunoglobulin E / Q000276:immunology; D007700:Kinetics; D008235:Lyngbya Toxins / Q000494:pharmacology; D008407:Mast Cells / Q000276:immunology / Q000378:metabolism*; D010703:Phorbol Esters / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*
D000936:Antigen-Antibody Complex; D000941:Antigens; D008235:Lyngbya Toxins; D010703:Phorbol Esters; C022176:teleocidins; D007073:Immunoglobulin E; D011493:Protein Kinase C; D002118:Calcium