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Adrenocorticotropic hormone stimulation of adrenal RNA polymerase I and III activities. Nucleotide incorporation into internal positions and 3' chain termini.
- Source :
-
Biochemistry [Biochemistry] 1975 Jul; Vol. 14 (13), pp. 2925-33. - Publication Year :
- 1975
-
Abstract
- In the presence of 50 mM (NH4)2SO4 and low concentrations of alpha-amanitin (7.7 mug/ml), adrenal nuclei synthesize predominately rRNA as characterized by size and base composition. Approximately 10% of the RNA synthesized under these conditions sediments at 4-5 S; this RNA synthesizing activity is inhibited by high concentrations of alpha-amanitin (231 mug/ml) indicating the presence of RNA polymerase III activity. ACTH administration to guinea pigs results in a twofold increase in adrenal nuclear RNA polymerase I and III activities at 14 hr of hormone treatment. Analysis of the amount of radiolabeled nucleoside triphosphate incorporated in vitro into 3' chain termini and into internal nucleotide positions has been utilized to measure the number of RNA chains and the average chain length synthesized in vitro. Incorporation into 3' chain termini is not changed by ACTH; incorporation into internal nucleotides is doubled in parallel with the increase in RNA polymerase I activity. These results are not due to an altered Km of RNA polymerase I for the four nucleoside triphosphates, nor to differential R Nase or phosphatase activity. These studies suggest that the regulation of RNA polymerase I by ACTH is accomplished in part through an increase in the rate of RNA chain elongation.
- Subjects :
- Amanitins pharmacology
Animals
Cell Nucleus drug effects
Centrifugation, Density Gradient
Cytosine Nucleotides metabolism
Female
Guinea Pigs
Kinetics
Molecular Weight
Nucleosides metabolism
Nucleotides analysis
Nucleotides metabolism
RNA biosynthesis
RNA, Ribosomal biosynthesis
Rats
Stimulation, Chemical
Time Factors
Uracil Nucleotides metabolism
Adrenal Cortex metabolism
Adrenal Glands metabolism
Adrenocorticotropic Hormone pharmacology
DNA-Directed RNA Polymerases metabolism
Transcription, Genetic drug effects
Subjects
Details
- Language :
- English
- ISSN :
- 0006-2960
- Volume :
- 14
- Issue :
- 13
- Database :
- MEDLINE
- Journal :
- Biochemistry
- Publication Type :
- Academic Journal
- Accession number :
- 167811
- Full Text :
- https://doi.org/10.1021/bi00684a021