Instability of Mammalian Liver Nuclear-Envelope Nucleoside Triphosphatase

1978 ◽  
Vol 6 (6) ◽  
pp. 1174-1177 ◽  
Author(s):  
ELIZABETH R. PORTEOUS ◽  
SARAH A. JAMIESON ◽  
PAUL S. AGUTTER
Keyword(s):  
Nuclear Envelope ◽  
Mammalian Liver ◽  
Nucleoside Triphosphatase

scholarly journals Ribonucleic acid stimulation of mammalian liver nuclear-envelope nucleoside triphosphatase. A possible enzymic marker for the nuclear envelope

1977 ◽  
Vol 162 (3) ◽  
pp. 671-679 ◽  
Author(s):  
P S Agutter ◽  
J R Harris ◽  
I Stevenson
Keyword(s):  
Nuclear Envelope ◽  
Specific Activity ◽  
Assay Medium ◽  
Exogenous Rna ◽  
Mammalian Liver ◽  
High Concentrations ◽  
Enzymic Marker ◽  
Stimulation Of ◽  
Nucleoside Triphosphatase

1. The specific activity of rat and pig liver nuclear-envelope nucleoside triphosphatase (EC 3.6.1.3) decreases when the system is depleted of RNA. The activity can be restored by adding high concentrations of yeast RNA to the assay medium. 2. Exogenous RNA also increases the activity of the enzyme in control envelopes (not RNA-depleted). The effect appears to be largely specific for poly(A) and poly(G); it is not stimulated by rRNA or tRNA preparations, ribonuclease-hydrolysed RNA, AMP, or double- or single-stranded DNA. 3. Inhibitors of the enzyme, in concentrations at which half-maximal inhibition of the enzyme is achieved, do not affect the percentage stimulation of the enzyme by yeast RNA. 4. The simulation is abolished by the inclusion of 150 mM-KCl or -NaCl in the assay medium, but not by increasing the assay pH to 8.5. 5. The results are discussed in the light of the possible role of the nucleoside triphosphatase in vivo in nucleo-cytoplasmic ribonucleoprotein translocation. 6. It is proposed that poly(G)-stimulated Mg2+-activated adenosine triphosphatase activity should be adopted as an enzymic marker for the nuclear envelope.

The role of protein phosphokinase and protein phosphatase during the nuclear envelope nucleoside triphosphatase reaction

1984 ◽  
Vol 773 (2) ◽  
pp. 308-316 ◽  
Author(s):  
Michael Bachmann ◽  
August Bernd ◽  
Heinz C. Schröder ◽  
Rudolf K. Zahn ◽  
Werner E.G. Müller
Keyword(s):  
Nuclear Envelope ◽  
Protein Phosphatase ◽  
Nucleoside Triphosphatase

Photoaffinity labeling of the major nucleoside triphosphatase of rat liver nuclear envelope

Biochemistry ◽  
1984 ◽  
Vol 23 (15) ◽  
pp. 3501-3507 ◽  
Author(s):  
Gary A. Clawson ◽  
C. H. Woo ◽  
Jane Button ◽  
Edward A. Smuckler
Keyword(s):  
Nuclear Envelope ◽  
Rat Liver ◽  
Photoaffinity Labeling ◽  
Nucleoside Triphosphatase

scholarly journals NUCLEAR MEMBRANES FROM MAMMALIAN LIVER

1970 ◽  
Vol 46 (2) ◽  
pp. 379-395 ◽  
Author(s):  
Werner W. Franke ◽  
Barbara Deumling ◽  
Baerbel Ermen ◽  
Ernst-Dieter Jarasch ◽  
Hans Kleinig
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Cytochrome B5 ◽  
Buoyant Density ◽  
Nuclear Pore ◽  
Nuclear Membranes ◽  
Dna And Rna ◽  
Mammalian Liver ◽  
Order Of Magnitude

Nuclear membranes were isolated from rat and pig liver by sonication of highly purified nuclear fractions and subsequent removal of adhering nucleoproteins in a high salt medium. The fractions were examined in the electron microscope by both negative staining and thin sectioning techniques and were found to consist of nuclear envelope fragments of widely varying sizes. Nuclear pore complex constituents still could frequently be recognized. The chemical composition of the nuclear membrane fractions was determined and compared with those of microsomal fractions prepared in parallel. For total nuclei as well as for nuclear membranes and microsomes, various enzyme activities were studied. The results indicate that a similarity exists between both fractions of cytomembranes, nuclear envelope, and endoplasmic reticulum, with respect to their RNA:protein ratio and their content of polar and nonpolar lipids. Both membranous fractions had many proteins in common including some membrane-bound enzymes. Activities in Mg-ATPase and the two examined cytochrome reductases were of the same order of magnitude. The content of cytochrome b5 as well as of P-450 was markedly lower in the nuclear membranes. The nuclear membranes were found to have a higher buoyant density and to be richer in protein. The glucose-6-phosphatase and Na-K-ATPase activities in the nuclear membrane fraction were very low. In the gel electrophoresis, in addition to many common protein bands, some characteristic ones for either microsomal or nuclear membranous material were detected. Significant small amounts of DNA and RNA were found to remain closely associated with the nuclear envelope fragments. Our findings indicate that nuclear and endoplasmic reticulum membranes which are known to be in morphological continuity have, besides a far-reaching similarity, some characteristic differences.

scholarly journals Importance of mammalian nuclear-envelope nucleoside triphosphatase in nucleo-cytoplasmic transport of ribonucleoproteins

1979 ◽  
Vol 182 (3) ◽  
pp. 811-819 ◽  
Author(s):  
P S Agutter ◽  
B McCaldin ◽  
H J McArdle
Keyword(s):  
Ionic Strength ◽  
Substrate Specificity ◽  
Nuclear Envelope ◽  
Nucleoside Triphosphate ◽  
Rna Transport ◽  
Isolated Nuclei ◽  
Cytoplasmic Rna ◽  
Cytoplasmic Transport ◽  
Nucleoside Triphosphatase

The nucleoside triphosphate-stimulated efflux of RNA from isolated nuclei was studied under a range of conditions, and the effects of these conditions on the process were compared with the properties of the nucleoside triphosphatase located in the pore complex. A marked similarity between the rate of efflux and the rate of nucleoside triphosphate hydrolysis was apparent, in terms of substrate specificity, sensitivity to treatment with insolubilized trypsin, kinetics and the effects of increased ionic strength and of many inhibitors. These results are taken, in view of earlier evidence, to suggest that the activity of the nucleoside triphosphatase is a prerequisite for nucleo-cytoplasmic RNA transport in vivo. There are some indications that the nuclear-envelope lipid is also involved in regulating the efflux process.

scholarly journals NUCLEAR MEMBRANES FROM MAMMALIAN LIVER

1970 ◽  
Vol 46 (2) ◽  
pp. 396-402 ◽  
Author(s):  
Hans Kleinig
Keyword(s):  
Nuclear Envelope ◽  
Surface Area ◽  
Lipid Composition ◽  
Total Surface Area ◽  
Striking Difference ◽  
Fourfold Increase ◽  
Nuclear Membranes ◽  
A Value ◽  
Mammalian Liver ◽  
Envelope Membranes

The qualitative and quantitative lipid composition of nuclei and nuclear membranes from pig and rat liver were determined. These determinations were compared with the corresponding data obtained for microsomes from the same material after similar treatments. The results indicate that, at least, by far the major part of the nuclear lipids is located in the membranes of the nuclear envelope. The phospholipid pattern of the nuclear membranes and the endoplasmic reticulum (ER) membranes in general is widely identical in both species. As a striking difference in the lipid composition, however, a fourfold increase of esterified cholesterol in the nuclear membranes was found. In a quantitative approach the ratio of total surface area of the nuclear lipids to the total surface area of the nuclear envelope membranes was calculated as being 3.6, a value which fairly approximates the requirements of a bimolecular lipid leaflet model.

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