scholarly journals Experimental conditions affecting ribonucleic acid polymerase in isolated rat liver nuclei. Effect of nucleoside triphosphate concentration, temperature, ammonium sulphate and heparin

1969 ◽  
Vol 112 (5) ◽  
pp. 721-727 ◽  
Author(s):  
F. Novello ◽  
F. Stirpe
Keyword(s):  
Ionic Strength ◽  
Rna Polymerase ◽  
Ammonium Sulphate ◽  
Rat Liver ◽  
High Ionic Strength ◽  
Isolated Rat Liver ◽  
Rat Liver Nuclei ◽  
Liver Nuclei ◽  
Low Ionic Strength ◽  
Isolated Rat

1. The conditions affecting the activity of RNA polymerase in isolated rat liver nuclei were studied with Mg2+ or Mn2+ as activating ions. 2. The enzyme assayed with Mg2+ and at low ionic strength is saturated by a lower concentration of nucleotide substrates than if assayed with Mn2+ at low ionic strength or with either ion at high ionic strength. 3. At low and at high ionic strength the incorporation of AMP is affected in a similar way by variations in the temperature of incubation. Preincubation at 37° impairs the AMP incorporation. 4. Heparin stimulates the RNA polymerase activity in the presence of Mn2+. 5. Both ammonium sulphate and heparin ‘restart’ the reaction if added after 15min., the effect being more marked with ammonium sulphate than with heparin, and also more marked in the presence of Mn2+ than of Mg2+. 6. α-Amanitin abolishes the effect of ammonium sulphate and of heparin.

scholarly journals Inhibition by α-amanitin of ribonucleic acid polymerase solubilized from rat liver nuclei

1970 ◽  
Vol 116 (2) ◽  
pp. 177-180 ◽  
Author(s):  
F. Novello ◽  
L. Fiume ◽  
F. Stirpe
Keyword(s):  
Rna Polymerase ◽  
Ammonium Sulphate ◽  
Rat Liver ◽  
Ribonucleic Acid ◽  
Isolated Rat Liver ◽  
Rat Liver Nuclei ◽  
Liver Nuclei ◽  
Isolated Rat

1. α-Amanitin inhibits in vitro the RNA polymerase solubilized from isolated rat liver nuclei. 2. In contrast with previous observations with whole nuclei, the inhibition occurs approximately to the same extent in the presence and in the absence of ammonium sulphate. 3. Evidence is presented that the toxin acts by interacting with the enzyme itself and not with DNA or other components.

scholarly journals The effects of copper and other ions on the ribonucleic acid polymerase activity of isolated rat liver nuclei

1969 ◽  
Vol 111 (1) ◽  
pp. 115-119 ◽  
Author(s):  
F. Novello ◽  
F. Stirpe
Keyword(s):  
Rna Polymerase ◽  
Ammonium Sulphate ◽  
Rat Liver ◽  
Ribonucleic Acid ◽  
Polymerase Activity ◽  
Isolated Rat Liver ◽  
Rat Liver Nuclei ◽  
Liver Nuclei ◽  
Isolated Liver ◽  
Isolated Rat

1. The effects of various ions on the Mg2+- and Mn2+/ammonium sulphate-activated RNA polymerase activities of isolated liver nuclei were studied. 2. The Mg2+-activated RNA polymerase reaction was inhibited by more than 60% by Cd2+, SeO32−, Be2+, Cu2+, Co2+, Ca2+ and La3+, all at 1mm concentrations. 3. The Mn2+/ammonium sulphate-activated RNA polymerase reaction was strongly inhibited by Hg2+, Cd2+, Cu2+ and Ag+. The effect of Hg2+, Cd2+ and Ag+ was relieved by cysteine or mercaptoethanol. 4. Inhibition by Cu2+ was not affected by addition of DNA, and was relieved only partially by EDTA or histidine. 5. No changes of RNA polymerase activities were observed in nuclei isolated from the liver of rats treated with copper albuminate.

scholarly journals Modulation by Exogenous Histones of Phosphorylation of Non-Histone Nuclear Proteins in Isolated Rat Liver Nuclei

1973 ◽  
Vol 248 (21) ◽  
pp. 7595-7600
Author(s):  
Edward M. Johnson ◽  
Giorgio Vidali ◽  
Virginia C. Littau ◽  
Vincent G. Allfrey
Keyword(s):  
Rat Liver ◽  
Nuclear Proteins ◽  
Isolated Rat Liver ◽  
Rat Liver Nuclei ◽  
Liver Nuclei ◽  
Isolated Rat

scholarly journals Cytochemical studies on the relation of nucleoside triphosphatase activity to ribonucleoproteins in isolated rat liver nuclei.

1980 ◽  
Vol 28 (1) ◽  
pp. 27-35 ◽  
Author(s):  
A Vorbrodt ◽  
G G Maul
Keyword(s):  
Nuclear Envelope ◽  
Rat Liver ◽  
Enzyme Reaction ◽  
Point Of View ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Isolated Rat Liver ◽  
Rat Liver Nuclei ◽  
Liver Nuclei ◽  
Isolated Rat

Cytochemical tests for nucleosidetriphosphatase (NTPase) and Bernhard's preferential staining for ribonucleoproteins (RNP) were applied to isolated rat liver nuclei. The strongest and most easily reproducible positive reaction for NTPase was detected at pH 7.7 with ATP and GTP. This reaction was activated by Mg2+ and Ca2+ and inhibited by Be2+, Zn2+, quercetin, and ribonuclease. The major sites of enzyme reaction were intranuclear RNA-containing structures. Incubation of nuclei in ATP-stimulated RNA-release medium eliminated a considerable part of the material showing both NTPase reaction and staining for RNP; the perichromatin granules disappeared, while interchromatin granules remained. NTPase activity in the nuclear envelope seems to be associated with the annular part of nuclear pore complexes (permanent component) and with RNP particles translocated through nuclear pores or attached to the surface of nuclei (transitional component). From a morphological point of view, these observations support previous biochemical data suggesting the existence of a connection between NTPase activity and the translocation of RNP particles through the nuclear envelope.

Sign in / Sign up

Export Citation Format

Share Document