Diacylglycerol-activated, calcium/phospholipid-dependent protein kinase (protein kinase C) activity in bovine thyroid.
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.
Friedman
Y
Y
Poleck
T
T
Henricks
L
L
Burke
G
G
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002417:Cattle; D003600:Cytosol / Q000201:enzymology; D004075:Diglycerides / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D005989:Glycerides / Q000494:pharmacology*; D007700:Kinetics; D010718:Phosphatidylserines / Q000494:pharmacology; D010743:Phospholipids / Q000494:pharmacology; D010766:Phosphorylation; D011493:Protein Kinase C; D011494:Protein Kinases / Q000302:isolation & purification / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013961:Thyroid Gland / Q000201:enzymology*
D004075:Diglycerides; D005989:Glycerides; D010718:Phosphatidylserines; D010743:Phospholipids; D011494:Protein Kinases; D011493:Protein Kinase C; D002118:Calcium; C013965:diolein