title: Cellular progesterone receptor phosphorylation in response to ligands activating protein kinases.
abstract: Progesterone receptors were immunoprecipitated with monoclonal antibodies KD68 from lysates of human breast carcinoma T47D cells labelled to steady state specific activity with 32Pi. The 120 kDa 32P-labelled progesterone receptor band was resolved by polyacrylamide gel electrophoresis and identified by autoradiography. Phosphoamino acid analysis revealed serine phosphorylation, but no threonine or tyrosine phosphorylation. Treatment of the 32Pi-labelled cells with EGF, TPA or dibutyryl cAMP had no significant quantitative effect on progesterone receptor phosphorylation, though the EGF receptor and the cAMP-dependent protein kinases have been reported to catalyze phosphorylation of purified avian progesterone receptor preparations in cell free systems. Progesterone receptor phosphorylation on serine residues was increased by 2-fold in cells treated with 10 nM progesterone; EGF had no effect on progesterone-mediated progesterone receptor phosphorylation.
mesh_terms: D000911:Antibodies, Monoclonal; D001943:Breast Neoplasms / Q000378:metabolism; D002460:Cell Line; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005260:Female; D006801:Humans; D007700:Kinetics; D008024:Ligands; D010710:Phosphates / Q000378:metabolism; D010761:Phosphorus Radioisotopes; D010766:Phosphorylation; D011374:Progesterone / Q000494:pharmacology; D011494:Protein Kinases / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; D008024:Ligands; D010710:Phosphates; D010761:Phosphorus Radioisotopes; D011980:Receptors, Progesterone; D011374:Progesterone; D004815:Epidermal Growth Factor; D011494:Protein Kinases