Protein kinase C alpha(1b)-adrenoceptor coimmunoprecipitation: effect of hormones and phorbol myristate acetate

alpha (1b)-Adrenoceptors immunoprecipitated with protein kinase C alpha, de lta, and epsilon isoforms under basal conditions and such coimmunoprecipita tions were increased in cells treated with phorbol myristate acetate. The i ncreased coimmunoprecipitations induced by phorbol myristate acetate were c oncentration-dependent and reached their maxima 1 to 2 min after the additi on of the tumor promoter. No coimmunoprecipitation of protein kinase C zeta and alpha (1b)-adrenoceptors was detected. Norepinephrine, endothelin-1, l ysophosphatidic acid and epidermal growth factor were also able to increase the coimmunoprecipitation of protein kinase C isoenzymes and alpha (1b)-ad renoceptors. These data support the idea that protein kinase-receptor compl exes might form and could be relevant in receptor desensitization. (C) 2001 Published by Elsevier Science B.V.