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As an indirect test of the possibility that cyclic AMP produces its stimulatory effects on the synthesis of tyrosine aminotransferase (L-tyrosine:2-oxoglutarate aminotransferase, EC 2.6.1.5) by stabilizing its mRNA, the kinetics of decline in the rate of synthesis of this enzyme was measured in rat hepatoma cells following inducer removal or addition of RNA synthesis inhibitors. In all cases in which cells were previously exposed to cyclic AMP, the decline in enzyme synthesis after removal of inducer or addition of inhibitors of RNA synthesis was 4 to 5 times more rapid than in cells exposed to a glucocorticoid (dexamethasone) which also induces the aminotransferase. Thus, it seems unlikely that cyclic AMP had been acting by stabilizing the mRNA that directs the synthesis of the aminotransferase. Possible explanations for these paradoxical results are suggested. A more rapid decline in enzyme synthesis was also seen in cells induced with both cyclic AMP and glucocorticoid, suggesting direct interaction between the two inducers.
E J Lewis, and
P Calie, and
W D Wicks
May 1982,
Hormone and metabolic research = Hormon- und Stoffwechselforschung = Hormones et metabolisme,
E J Lewis, and
P Calie, and
W D Wicks
February 1981,
Journal of steroid biochemistry,
E J Lewis, and
P Calie, and
W D Wicks
April 1975,
Journal of cellular physiology,
E J Lewis, and
P Calie, and
W D Wicks
October 1977,
The Journal of biological chemistry,
E J Lewis, and
P Calie, and
W D Wicks
May 1979,
Cell biology international reports,
E J Lewis, and
P Calie, and
W D Wicks
June 1975,
Proceedings of the National Academy of Sciences of the United States of America,
E J Lewis, and
P Calie, and
W D Wicks
May 1980,
The Journal of biological chemistry,
E J Lewis, and
P Calie, and
W D Wicks
September 1980,
The Biochemical journal,
E J Lewis, and
P Calie, and
W D Wicks
June 1971,
Experimental cell research,
E J Lewis, and
P Calie, and
W D Wicks
January 1986,
Journal of cyclic nucleotide and protein phosphorylation research,
