Response to Letters Regarding Article, “Evidence for Statin Pleiotropy in Humans: Differential Effects of Statins and Ezetimibe on Rho-Associated Coiled-Coil Containing Protein Kinase Activity, Endothelial Function, and Inflammation”

Differential effects of epigenetic tumor promoters and a genotoxic carcinogen on hepatic cytosolic cyclic adenosine 3′,5′-monophosphate-dependent protein kinase (CAMP-PK) were studied in vitro, since this enzyme is one of the major mediators of cell membrane permeability. Mirex (dodecachlorooctahydro-1,3,4-metheno-2H-cyclobuto[cd]pentalene), like phorbol ester TPA (12-0-tetradecanoylphorbol-13-acetste), caused significant inhibition of cAMP-dependent protein kinase activity ratio, whereas DDT [p, p′-trichlorobis(p-chlorophenyl)ethane] produced concentration-dependent changes. Diethylnitrosamine (DEN) and phenobarbitol (PB), however, showed a significant enhancement of the activity ratio. Interestingly, combinations of mirex, DDT with PB or DEN resulted in the potentiation of CAMP-dependent protein kinase activity in contrast to their effects when used separately. The results suggest that the influences of mirex and TPA in vitro on CAMP-PK are different from those observed in other cell and intact animal systems.

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Effect of Thrombin on Phosphorylation of Platelet Membrane Proteins

Thrombosis and Haemostasis ◽

10.1055/s-0038-1647962 ◽

1976 ◽

Vol 35 (03) ◽

pp. 635-642 ◽

Cited By ~ 4

Author(s):

M Steiner

Keyword(s):

Protein Kinase ◽

Kinase Activity ◽

Qualitative Change ◽

Protein Kinase Activity ◽

Protein Substrates ◽

Phosphoprotein Phosphatase ◽

Progressive Loss ◽

Platelet Membranes ◽

Endogenous Protein ◽

Considerable Loss

SummaryThe effect of thrombin on the phosphorylating activity of platelet membranes was compared to that of trypsin. Preincubation of non-32P phosphorylated platelet membranes with or without either of these two enzymes resulted in a considerable loss of membrane protein kinase activity which was most severe when trypsin was used. Protein kinase activity and endogenous protein acceptors decreased in parallel. 32P-phosphorylated membranes showed a slow but progressive loss of label which was accelerated by trypsin. Thrombin under these conditions prevented the loss of 32P-phosphate. These results are interpreted to indicate a thrombin-induced destruction of a phosphoprotein phosphatase. The protein kinase activity of phosphorylated platelet membranes using endogenous or exogenous protein substrates showed a significant reduction compared to non-phosphorylated membranes suggesting a deactivation of protein kinase by phosphorylation of platelet membranes. Neither thrombin nor trypsin caused a qualitative change in the membrane polypeptides accepting 32P-phosphate but resulted in quantitative alterations of their ability to become phosphorylated.

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Faculty Opinions recommendation of Drosophila doubletime mutations which either shorten or lengthen the period of circadian rhythms decrease the protein kinase activity of casein kinase I.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1016883.201562 ◽

2004 ◽

Author(s):

Louis Ptacek

Keyword(s):

Protein Kinase ◽

Circadian Rhythms ◽

Kinase Activity ◽

Casein Kinase ◽

Protein Kinase Activity ◽

Casein Kinase I

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