Synthesis and maturation of ribosomal ribonucleic acids in isolated HeLa cell nuclei. A tracer study on the topology of the 45S precursor of ribosomal ribonucleic acids

Hadjiolov, A.A.; Milchev, G.

doi:10.1042/bj1420263

Cited by 28 publications

(3 citation statements)

References 38 publications

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“…The radioactivity per nucleus incorporated into 28S or 18S species in the whole nuRNA, npRNA or cytoplasmic RNA fractions (Rx; x-28S or 18S rRNA) was calculated by the equation: NaF/0.05% fl-mercaptoethanol/12.5% glycerol/ 0.5 mM-EDTA containing 1,ug of a-amanitin/ml, 0.3 mM each of ATP, GTP and CTP, and 0.017 mM-[3H]UTP (sp. radioactivity 2 Ci/mmol) in a final volume of 0.120ml, containing lO,ug of nucleolar DNA at 200 C. Samples (0.020 ml) were taken every 5min and processed further as described by Hadjiolov & Milchev (1974). Enzyme activity was estimated in the absence or presence of 150,ug of heparin/ml.…”

Section: Isolation Ofnucleolimentioning

confidence: 99%

Transcriptional control of ribosome production in regenerating rat liver

Dabeva¹,

Dudov²

1982

Biochemical Journal

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Kinetic experiments of labelling in vivo with [14C]orotate of cellular free UMP and/or UTP, nucleolar, nucleoplasmic and cytoplasmic rRNA in normal and 12 h-regenerating rat liver were performed. The specific-radioactivity curves obtained were analysed by computer and the rates of synthesis of precursor rRNA (45S pre-rRNA) and cytoplasmic 28S and 18S rRNA calculated. (a) The rates of synthesis of 45S pre-rRNA in normal and regenerating rat liver are 1400 and 3700 molecules/min per nucleus respectively; (b) the average rates of formation of mature 28S and 18S rRNA are identical with the rates of synthesis of 45S pre-rRNA in both normal and regenerating rat liver. Thus the synthesis of rRNA in 12h-regenerating rat liver is activated 2.7-fold. The analysis of rRNA synthesis in isolated nucleoli also shows a 2.7-fold stimulation of transcription in regenerating liver. It is concluded that all the 45S pre-rRNA molecules synthesized are processed and transferred as 28S and 18S rRNA in the cytoplasm, i.e. degradation (wastage) of newly synthesized ribosomes in the nucleus does not occur in both normal and regenerating rat liver. Thus the enhanced production of ribosomes in regenerating rat liver is regulated only at the transcriptional level.

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Section: Isolation Ofnucleolimentioning

confidence: 99%

Transcriptional control of ribosome production in regenerating rat liver

Dabeva¹,

Dudov²

1982

Biochemical Journal

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“…(f) The polarity in the labelling of primary pre-rRNA (Hadjiolov & Milchev, 1974) does not interfere substantially at labelling periods longer than 20min. Under our conditions (see Fig.…”

Section: (B)mentioning

confidence: 99%

Processing and migration of ribosomal ribonculeic acids in the nucleolus and nucleoplasm of rat liver nuclei

Dudov¹,

Dabeva²,

Hadjiolov³

et al. 1978

Biochemical Journal

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Kinetic studies on the labelling in vivo with [14C]orotate of rat liver nucleolar and nucleoplasmic pre-rRNA (precursor of rRNA) and rRNA, isolated from detergent-purified nuclei, were carried out. The mathematical methods used for the computer analysis of specific-radioactivity curves are described. Evaluation of the experimental data permitted the selection of the most probable models for the processing of pre-rRNA and the nucleo-cytoplasmic transfer of rRNA. It was shown that considerable flexibility exists in the sequence of endonuclease attacks at critical sites of 45 and 41 S pre-rRNA chains, resulting in the simultaneous occurrence of several processing pathways. However, the phosphodiester bonds involved in the formation of mature 28 and 18 S rRNA appear to be protected until the generation of their immediate pre-rRNA. The turnover rates and half-lives of all pre-rRNA and rRNA pools were determined. The turnover rate of 45 S pre-rRNA corresponds to the formation of 1100 ribosomes/min per nucleus. The model for the nucleolus-nucleoplasm-cytoplasm migration of rRNA includes a 'nucleoplasm' compartment in which the small ribosomal subparticle is in rapid equilibrium with the respective cytoplasmic pool. At equimolar amounts of nuclear 28 and 18 S rRNA this model explains the faster appearance of labelled small ribosomal subparticles in the cytoplasm simultaneous with a lower labelling of nuclear 18 S rRNA as compared with 28 S rRNA.

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“…Smallmolecular-weight RNA and poly(A) fragments were analyzed by gel electrophoresis in 10 % acrylamide/7 M urea [15]. The radioactivity in the gel slices was determined as described earlier [16].…”

Section: Analysis Of the Poly(a) Polymerase Reaction Productmentioning

confidence: 99%

Primer Specificity of Ribosome‐Associated Poly(A) Polymerase from Ehrlich Ascites Tumour Cells

Milchev¹,

Avramova²,

Hadjiolov³

1980

European Journal of Biochemistry

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The reaction product of the ribosomal poly(A) polymerase [ATP(UTP) :RNA ucleotidyltra Sferase] is analyzed. Two systems are used in vitro: (a) isolated polyribosomes with endogenous enzyme and RNA primer and (b) purified enzyme with total polyribosomal RNA as primer. In the polyribosome system about 50 % of the [3H]AMP label is in poly(A)-containing mRNA. This RNA displays a heterogeneous size ditribution in the range of 8 -30 S with a maximum at about 14 S. Upon denaturation the maximum is shifted towards the 10-S zone. The poly(A) polymerase catalyzes the addition of 12-18 adenylate residues to pre-existing mRNA poly(A) sequences of 40-160 residues. The [3H]AMP incorporated into poly(A)-lacking RNA is mainly in a fraction with an electrophoretic mobility corresponding to 4-S RNA. In the purified enzyme system, specificity towards poly(A)-containing mRNA is lost to a considerable extent. Only 10% of the [3H]AMP label is retained by oligo(dT)-cellulose. The bulk of the product is in 18-S rRNA and heterogeneous small molecular weight RNA.We conclude that the ribosome-associated poly(A) polymerase is most likely the enzyme responsible for the cytoplasmic polyadenylation of poly(A)-containing mRNA in vivo.

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Synthesis and maturation of ribosomal ribonucleic acids in isolated HeLa cell nuclei. A tracer study on the topology of the 45S precursor of ribosomal ribonucleic acids

Cited by 28 publications

References 38 publications

Transcriptional control of ribosome production in regenerating rat liver

Transcriptional control of ribosome production in regenerating rat liver

Processing and migration of ribosomal ribonculeic acids in the nucleolus and nucleoplasm of rat liver nuclei

Primer Specificity of Ribosome‐Associated Poly(A) Polymerase from Ehrlich Ascites Tumour Cells

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