EFFECTS OF INSULIN AND PHORBOL ESTERS ON SUBCELLULAR-DISTRIBUTION OF PROTEIN-KINASE-C ISOFORMS IN RAT ADIPOCYTES

Effects of insulin and phorbol esters on subcellular distribution of protein kinase C (PKC) isoforms were examined in rat adipocytes. Both agonists provoked rapid decreases in cytosolic, and/or increases in membrane. immunoreactive PCK-alpha, PKC-beta, PKC-gamma and PKC-epsilon. Effects of phorbol esters on PCK-alpha redistribution to the plasma membrane, however, were much greater than those of insulin. In contrast. insulin, but not phorbol esters, stimulated the translocation of PKC-beta to the plasma membrane, and provoked changes in PKC-zeta redistribution. Neither agonist altered subcellular distribution of PKC-delta, which was detected only in membrane fractions. Our findings indicate that insulin and phorbol esters have overlapping and distinctly different effects on the subcellular redistribution of specific PKC isoforms.