title: Protein kinase C in fibroblasts. Characteristics of its intracellular location during growth and after exposure to phorbol esters and other mitogens.
abstract: Using an N-bromosuccinimide cleavage fragment of histone H1 as a relatively specific substrate for protein kinase C, we evaluated the partitioning of this kinase activity between soluble and particulate cellular fractions in 3T3-L1 fibroblasts. In confluent, serum-deprived cells, protein kinase C activity was approximately equally divided between soluble and detergent-extractable particulate fractions; both rapidly growing and transformed cells appeared to contain higher levels of particulate enzyme activity. Soluble protein kinase C activity and immunoreactivity decreased to virtually undetectable levels after exposure of the cells to phorbol 12-myristate 13-acetate (PMA), associated with a commensurate increase in particulate kinase activity and immunoreactivity. In intact cells, PMA appeared to cause a shift of immunoreactive protein kinase C from the cytosol to the perinuclear region, as assessed by immunofluorescent microscopy; however; subcellular fractionation revealed that PMA caused increases in the protein kinase C activity associated primarily with non-nuclear membranes. Exposure of the cells to sn-1,2-dioctanoylglycerol resulted in a modest and transient membrane association of protein kinase C, whereas platelet-derived growth factor, fibroblast growth factor, and bombesin caused no detectable increases in the membrane association of the kinase. Activation of protein kinase C by growth factors in fibroblasts may occur without the gross disturbances in intracellular kinase location which occur in response to phorbol esters.
mesh_terms: D000818:Animals; D001839:Bombesin / Q000494:pharmacology; D001974:Bromosuccinimide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005346:Fibroblast Growth Factors / Q000494:pharmacology; D005347:Fibroblasts / Q000201:enzymology*; D006651:Histocytochemistry; D007425:Intracellular Membranes / Q000201:enzymology; D051379:Mice; D008934:Mitogens / Q000494:pharmacology*; D008970:Molecular Weight; D010703:Phorbol Esters / Q000494:pharmacology*; D011493:Protein Kinase C / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D008934:Mitogens; D010703:Phorbol Esters; D005346:Fibroblast Growth Factors; D011493:Protein Kinase C; D001974:Bromosuccinimide; D013755:Tetradecanoylphorbol Acetate; D001839:Bombesin