Studies on the nature of polysomes

Munro, AJ; Jackson, RJ; Körner, A.

doi:10.1042/bj0920289

Cited by 240 publications

(104 citation statements)

References 31 publications

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“…The increase in polyribosomal RNA was 30% and this was associated with a shift in the ratio free/membrane-bound plus membrane-free polyribosomes from 59 to 32% in the phenobarbitone-treated group. Since this latter value is similar to that in normal livers (Webb et al, 1965;Blobel & Potter, 1967; G-25 increases the specific radioactivity of the synthesized protein when the particulate fraction is incubated with radioactive amino acid (Munro et al, 1964). Since the effect of phenobarbitone on protein synthesis might be mediated by changes in the lowmolecular-weight components that are removed by Sephadex treatment, all incorporation experiments were done with fractions before and after Sephadex treatment.…”

Section: Effect Ofphenobarbitone On Liver Weightmentioning

confidence: 81%

“…Since the protein-synthetic activity of the isolated polyribosomes plus cell sap depends on the ratio rRNA incubated/cell-sap protein (Ragnotti, 1971;Lowe & Hallinan, 1973), care was taken to keep this ratio constant and above the limiting value of 50 (Munro et al, 1964). After 30min at 370C without shaking, the incorporation process was stopped by the addition of 1.4ml of an ice-cold solution, containing IOmM-L-leucine, 10mM-EDTA (disodium salt) and 154mM-NaCl.…”

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confidence: 99%

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The effect of phenobarbitone on protein synthesis by liver polyribosomes in fed and starved rats

Ragnotti

Aletti

1975

Biochemical Journal

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1. The effect of phenobarbitone on the rate of protein synthesis and on the sedimentation patterns of various liver subcellular fractions containing ribosomes was studied in rats. 2. Phenobarbitone treatment increased the incorporation of [14C]leucine into protein by all preparations, provided they had not been subjected to preliminary treatment with Sephadex G-25. The phenobarbitone-induced effect on incorporation was associated with a gain in liver weight and a higher degree of polyribosomal aggregation. 3. Preparations that were treated with Sephadex G-25 incorporated more radioactivity into protein, but did not show the response to phenobarbitone treatment. 4. When the influence of starvation and phenobarbitone was studied separately on membrane-bound and membrane-free polyribosomes, it was shown that whereas both classes of polyribosomes were affected by starvation, apparently only the former class was susceptible to phenobarbitone stimulation of protein synthesis. 5. The decreased capacity for protein synthesis of polyribosomes from starved rats was independent of their association with the membranes of the endoplasmic reticulum, but resulted from polyribosomal disaggregation, from an intrinsic defect of the polyribosomes themselves and from changes in composition of the cell sap. 6. The results are discussed in relation to the problem ofthe control ofprotein biosynthesis and of the functional separation of membrane-bound and membrane-free polyribosomes.

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Section: Effect Ofphenobarbitone On Liver Weightmentioning

confidence: 81%

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confidence: 99%

The effect of phenobarbitone on protein synthesis by liver polyribosomes in fed and starved rats

Ragnotti

Aletti

1975

Biochemical Journal

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“…Actinomycin, when given 2 hours prior to the administration of 32 P, inhibited equally the labeling of 28 S RNA and RNA in the 4 to 18 S region (Table 2).…”

Section: P Subceuular Fractionation Into Microsomal (A) and "Myofibrmentioning

confidence: 99%

“…These curves demonstrate that the initial rate of increase of specific activity of 4 to 18 S RNA is greater than that of 28 S Patterns of labeling of microsomal and "myofibrillar-nuclear" fractions. Twenty rats were injected with 2 iic/g body weight of "P; 6 hours later they were killed, and the hearts from 10 unlabeled animals were added to those which had received 32 RNA. It is also clear that the specific activity of the 4 to 18 S RNA reaches a plateau by 6 hours, whereas that of 28 S RNA increases in a biphasic manner over the whole 24-hour period of observation and approximates specific activity of 4 to 18 S RNA by about 24 hours.…”

Section: Posner Fanburgmentioning

confidence: 99%

Studies on Components of RNA in Cardiac Muscle with Emphasis on the Rapidly Labeled 4 to 18 S Fraction

Posner

Fanburg

1966

Circulation Research

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Studies on RNA from cardiac muscle of rats were performed by labeling the RNA with 32 P, extracting it with phenol, and purifying it prior to fractionating and analyzing it on a sucrose density gradient. The major components of RNA found had sedimentation values of 28, 18, and 4 S. Early 32 P-labeIed RNA ranged in size from 4 to > 45 S. Characterization of RNA from 4 to 18 S showed it to be more rapidly labeled and to have a higher turnover rate than 28 S RNA, to be located, at least in part, in the microsomes, and to have a base composition lower in guanine and cytosine content than 28 S RNA. Labeling of 4 to 18 S and 28 S RNA was equally inhibited by actinomycin. The possibility that 4 to 18 S RNA may represent a portion of messenger RNA in cardiac muscle is considered.ADDITIONAL KEY WORDS 32 P-labeIed RNA phenol extraction actinomycin subcellular particles sucrose-density-gradient analysis fractionation of RNA base analysis of RNA messenger RNA turnover rate of RNA• The messenger hypothesis postulates that RNA molecules transfer information from DNA to ribosomes (1). Studies of bacteria have demonstrated species of RNA thought to function in this capacity: the important characteristics are rapidity of labeb'ng by RNA precursor molecules, decreased stability relative to that of ribosomal RNA, a base composition that resembles that of DNA, heterogeneity of molecular size, a capacity for hybrid formation with homologus DNA, localization in polysomes, and a stimulatory effect on amino-acid incorporation in vitro (2-11).A heterogeneous, rapidly labeled RNA has been demonstrated in a number of mammalian tissues (12-27) as well as in germinating plants (28) and yeast cells (29). No comparable material has been characterized in striated muscle although its existence in this This investigation was supported by grants (5T1 HE 5391 and 2R01 HE 06924) from the U. S. Public Health Service.Accepted for publication July 16, 1966. tissue has been suggested (30). The heart is more suitable than skeletal muscle for the study of RNA synthesis because considerably more cardiac muscle RNA can be labeled in vivo (Fig. 1). In this communication, we wish to record the existence of a heterogeneous, rapidly labeled RNA fraction in cardiac muscle of the rat and to delineate some of its pertinent properties. Methods Animals.Male albino rats, weighing 90 to 120 g except when otherwise noted, were used; they were maintained on Purina chow ad lib. until they were killed.Materials. Phenol, 8-hydroxyquinoline, bentonite, and diphenylamine (special indicator grade) were purchased from the Fisher Scientific Company. Sodium dodecyl sulfate and yeast RNA (type XI) were obtained from the Sigma Chemical Company.3 -P was obtained from the New England Nuclear Corporation.Labeling of RNA. The tail veins of rats lightly anesthetized with ether were injected with carrierfree H R 3 -PO 4 diluted in 0.5 to 1.0 ml of 0.9S NaCl. Animals were killed by decapitation at varying times after injection of the label. The heart, and sometimes the skelet...

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“…Ribosomes (IOO,OOO g sediment) were sedimented from the 30,000 g supernatant fluid by centrifuging at ~oo,ooog for 3 hr then washed and resuspended in the buffer described by Munro, Jackson & Korner (1964).…”

Section: Location Of Nisin In Streptococci =73mentioning

confidence: 99%

The Location of Nisin in the Producer Organism, Streptococcus lactis

White

Hurst

1968

Journal of General Microbiology

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S U M M A R YStreptococcus lactis organisms grown in a glucose-containing medium pH maintained at pH 6.8 (neutral cocci) contained three-to seven-fold more nisin/unit dry weight than cocci grown in the same medium without pH control (acid cocci, terminal pH 4.2). After chemical fractionation of acid cocci 57 % of the nisin was found in the fraction soluble in aqueous ethanol and 36 yo in a trypsin-insoluble residue. After fractionation of broken cocci (acid and neutral) by differential centrifugation up to 60 % of the nisin was found in the 10,000 g sediment (walls). Nisin was also present in the 30,000 g sediment (membranes) and the IOO,OOO g sediment (ribosomes). The major difference between acid and neutral cocci was in the ~oo,ooog supernatant fluid (cell sap); cell sap from neutral cocci was 0.28% nisin whereas that from acid cocci was 0.04% nisin. Analysis of the cell wall indicated that it was composed of mucopeptide and polysaccharide. Teichoic acid could not be extracted. The polysaccharide was soluble in hot formamide and accounted for one-third of the dry weight of the wall; it contained rhamnose, galactose, glucose, glucosamine in the molar ratio of 5: I : I : I . Cell walls contributed 31 Yo to the dry weight of acid cocci and 42 % to the dry weight of neutral cocci.

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Studies on the nature of polysomes

Cited by 240 publications

References 31 publications

The effect of phenobarbitone on protein synthesis by liver polyribosomes in fed and starved rats

The effect of phenobarbitone on protein synthesis by liver polyribosomes in fed and starved rats

Studies on Components of RNA in Cardiac Muscle with Emphasis on the Rapidly Labeled 4 to 18 S Fraction

The Location of Nisin in the Producer Organism, Streptococcus lactis

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