Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.13 (protein kinase C)
 49,245 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Bovine thyroid 100,000 X g supernatant contained diacylglycerol-activated, calcium/phospholipid-dependent protein kinase (protein kinase C). The protein kinase C was partially purified using ion-exchange chromatography and characterized. Substrate specificity studies revealed that the enzyme was most active when histone F1 was used as substrate. The thyroid protein kinase C was not stimulated by Ca2+ or phosphatidylserine (PS), but was stimulated by the combination of the two by 570%. Diolein stimulated the kinase by increasing its sensitivity to Ca2+. Other phospholipids could not substitute for PS and were ineffective in stimulating the protein kinase C in the absence of diolein. However, in the presence of diolein some of the other phospholipids were stimulatory albeit not to the extent of PS. Quercitin, a protein kinase C inhibitor in other systems, inhibited the thyroid enzyme in a dose-related manner. Protein kinase C could also be demonstrated using endogenous thyroid proteins as substrate. Separation of these 32P-labelled proteins by electrophoresis and subsequent autoradiography revealed that three proteins were phosphorylated by the protein kinase C of approximate molecular weights 60,000, 45,000, and less than 29,000. These results offer a possible mechanism by which Ca2+ and/or diacylglycerol effects may be mediated in thyroid.
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PMID:Diacylglycerol-activated, calcium/phospholipid-dependent protein kinase (protein kinase C) activity in bovine thyroid. 316 11

The phorbol ester, TPA, induced the intracellular redistribution of protein kinase C in intact thyroid cells; it caused within 5 min of incubation a 90% decrease of the cytosolic protein kinase C and an increase of the membrane-associated enzyme activity which appeared to be fully activated by TPA. TSH at concentrations which gave the maximal stimulation on various parameters of iodine metabolism induced the translocation of only 10-15% of protein kinase C from the cytosol to the membrane fraction. TPA induced a 2-fold increase in the incorporation of [32P]phosphate into cellular proteins and selectively activated the phosphorylation of two molecular species: a 180,000 Da protein and to a lesser extent a 170,000 Da protein in dispersed pig thyroid cells prelabeled with [32P]orthophosphate. The effect of TPA was maximum after 5 min of incubation and was concentration-dependent between 1 nM and 1 microM. The two phosphorylated substrates were only found in the cytosolic fraction. The TPA-induced phosphorylation of the 180,000 Da protein was observed in thyroid cells in suspension, in thyroid cell monolayers and follicle-like reassociated cells. In these three experimental situations, the 180,000 Da protein was not phosphorylated in response to TSH. Incubation of thyroid cell cytosolic fraction in the presence of [32P]ATP with calcium and phospholipid led to the phosphorylation of few proteins among which a 180,000 Da component. These proteins were not phosphorylated in the cytosol of TPA-treated cells, a finding in agreement with the translocation of protein kinase C. These results indicate that (1) the activation-translocation of thyroid protein kinase C induced by TPA is associated with the phosphorylation of selective substrates, and (2) TSH, even at high concentration, failed to exert the same action as TPA on protein kinase C in pig thyroid cells.
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PMID:Protein kinase C in pig thyroid cells: activation, translocation and endogenous substrate phosphorylating activity in response to phorbol esters. 367 97