Phorbol esters, protein kinase C, and thyroxine 5'-deiodinase in brown adipocytes.
Protein kinase C activity has been identified in the rat brown adipocyte. About 60% of this activity is found in the cytosolic fraction under basal conditions, and 12-O-tetradecanoylphorbol 13-acetate (TPA) causes a rapid shift from the cytosol to the particulate fraction. Norepinephrine and phenylephrine cause a similar redistribution that can be blocked by prazosin but not by alprenolol. alpha 1-Adrenergic agonists cause three- to fivefold stimulation of type 2 iodothyronine 5'-deiodinase activity in brown adipocytes. TPA has no effect on basal deiodinase activity and reduces the response of the enzyme to alpha 1-adrenergic agonists. These results suggest that the translocation of protein kinase C from cytosol to particulate fraction is not sufficient to increase deiodinase activity but can modulate the alpha 1-adrenergic agonist-mediated responses in these cells.
D002001:Adipose Tissue, Brown / Q000166:cytology / Q000201:enzymology*; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D007453:Iodide Peroxidase / Q000378:metabolism*; D008297:Male; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D000316:Adrenergic alpha-Agonists; D007453:Iodide Peroxidase; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate