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The regulation of hepatic tyrosine aminotransferase.
Biochim Biophys Acta. 1981 Nov 05; 677(3-4):433-44.BB

Abstract

Tyrosine aminotransferase induction has been studied in hepatocytes from untreated, partially and fully glucocorticoid-induced rats: enzyme activities were initially 12.9 +/- 1.7 (n = 16), 41.4 +/- 3.2 (n = 6) and 117.9 +/- 10.5 (n = 7) munits/mg protein, respectively. Untreated or fully induced hepatocytes maintain initial levels, whereas partially induced hepatocytes increase their tyrosine aminotransferase activity even in the presence of actinomycin D. Fully induced hepatocytes possess a normal protein synthetizing machinery and the mechanisms to degrade selectively tyrosine aminotransferase. The effect of progesterone treatment is consistent with these cells retaining a high dexamethasone level. Glucagon induces tyrosine aminotransferase via its second messenger, cyclic AMP. This induction decreases dramatically with in vivo glucocorticoid treatment. Time courses and effects of inhibitors are consistent with these in vivo and in vitro treatments being alternative methods of inducing tyrosine aminotransferase by the same basic pretranslational step.

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Publisher Full Text

Authors

Evans PJ
No affiliation info available

MeSH

AnimalsBucladesineDactinomycinDexamethasoneEnzyme InductionGene Expression RegulationGlucagonInsulinLiverMaleProgesteroneRatsRats, Inbred StrainsTyrosine Transaminase

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

6117330

Citation

Evans, P J.. "The Regulation of Hepatic Tyrosine Aminotransferase." Biochimica Et Biophysica Acta, vol. 677, no. 3-4, 1981, pp. 433-44.
Evans PJ. The regulation of hepatic tyrosine aminotransferase. Biochim Biophys Acta. 1981;677(3-4):433-44.
Evans, P. J. (1981). The regulation of hepatic tyrosine aminotransferase. Biochimica Et Biophysica Acta, 677(3-4), 433-44.
Evans PJ. The Regulation of Hepatic Tyrosine Aminotransferase. Biochim Biophys Acta. 1981 Nov 5;677(3-4):433-44. PubMed PMID: 6117330.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The regulation of hepatic tyrosine aminotransferase. A1 - Evans,P J, PY - 1981/11/5/pubmed PY - 1981/11/5/medline PY - 1981/11/5/entrez SP - 433 EP - 44 JF - Biochimica et biophysica acta JO - Biochim Biophys Acta VL - 677 IS - 3-4 N2 - Tyrosine aminotransferase induction has been studied in hepatocytes from untreated, partially and fully glucocorticoid-induced rats: enzyme activities were initially 12.9 +/- 1.7 (n = 16), 41.4 +/- 3.2 (n = 6) and 117.9 +/- 10.5 (n = 7) munits/mg protein, respectively. Untreated or fully induced hepatocytes maintain initial levels, whereas partially induced hepatocytes increase their tyrosine aminotransferase activity even in the presence of actinomycin D. Fully induced hepatocytes possess a normal protein synthetizing machinery and the mechanisms to degrade selectively tyrosine aminotransferase. The effect of progesterone treatment is consistent with these cells retaining a high dexamethasone level. Glucagon induces tyrosine aminotransferase via its second messenger, cyclic AMP. This induction decreases dramatically with in vivo glucocorticoid treatment. Time courses and effects of inhibitors are consistent with these in vivo and in vitro treatments being alternative methods of inducing tyrosine aminotransferase by the same basic pretranslational step. SN - 0006-3002 UR - https://www.unboundmedicine.com/medline/citation/6117330/The_regulation_of_hepatic_tyrosine_aminotransferase_ L2 - https://linkinghub.elsevier.com/retrieve/pii/0304-4165(81)90257-9 DB - PRIME DP - Unbound Medicine ER -