Séparation des particules ribonucléoprotéiques (Hn‐RNP) des noyaux de cellules L, en deux classes, par centrifugation isopycnique en gradients de métrizamide

Houssais, Jean‐François

doi:10.1016/0014-5793(75)81123-9

Cited by 18 publications

(2 citation statements)

References 21 publications

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“…2-(3 acetamido-5-N-methylacetamido-2,4,6-triiodobenzamido)-2-deoxy-D-glucose (Metrizamide, Nyegaard and Co A/S, Oslo) was dissolved in 20 mM Triethanolamine-HCl, pH 7.4, 25 mM KCl, 3 mM MgCl2, 10 mM mercaptoethanol. Two methods were used for making the gradients: Method I: Fractions of sucrose gradients were pooled and 1.8 ml were layered on 3.4 ml of a solution of 40 % (w/v) of metrizamide (7).…”

Section: Introductionmentioning

confidence: 99%

Metrizamide dissociates nuclear particles containing heterogeneous nuclear RNA

Gattoni¹,

Stévenin²,

Jacob³

1977

Nucl Acids Res

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Metrizamide gradients were tested for the possible fractionation of the constitutive units of nuclear particles. Material from 35-55 S monoparticles was indeed distributed along the gradient but rerun experiments, CsCl density determinations, formaldehyde fixation prior to centrifugation suggested that the separation was due to dissociation or (and) action of endogeneous ribonucleases rather than to monoparticle fractionation. That dissociation had indeed occured was confirmed by the study of 60-110 S polyparticles. They were dissociated into ribonucleoproteins rich in phosphoproteins and into free proteins. These products were essentially similar to those obtained after NaCl treatment of the particles though the modes of action of metrizamide and NaCl are likely to be different. The loss of proteins from particles reaches 60-70% and we conclude that metrizamide gradients are not utilizable for the fractionation of the units of nuclear particles.

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Section: Introductionmentioning

confidence: 99%

Metrizamide dissociates nuclear particles containing heterogeneous nuclear RNA

Gattoni¹,

Stévenin²,

Jacob³

1977

Nucl Acids Res

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“…6). In other systems messenger RNP (mRNP) usually bands in metrizamide at a lower density than the ribosomes (3,8), whereas purified RNA bands at 1.17 g/cm3. The non-adenylated RNA which sediments between 20S and 80S (Fig.…”

Section: Methodsmentioning

confidence: 99%

Stage-specific synthesis of proteins complexed to ribonucleoprotein particles and ribosomes in zoospores of Blastocladiella emersonii.

Jaworski¹,

Stumhofer²

1981

Mol. Cell. Biol.

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In Blastocladiella emersonii zoospores, a set of proteins was found associated with the ribosomes and free ribonucleoprotein particles distinct from the ribosomes and polyribosomes. These proteins were designated P120, P105, P64, P56, and P42 based on their molecular weights determined by gel electrophoresis. Synthesis of these proteins was detected only during late sporulation just before the time polyadenylated ribonucleic acid accumulates in the sporangia. These proteins banded in isopycnic metrizamide gradients at densities of 1.31 and 1.27 g/cm3, which corresponded to the densities of the ribosomes and free ribonucleoprotein particles, respectively. Comparison of the distribution of the proteins in sucrose versus metrizamide gradients suggested that P105 was removed from the free ribonucleoprotein particles before complexing with the ribosomes. During germination, these proteins disappeared from the ribosomal fractions, with kinetics corresponding to the resumption of protein synthesis. Another protein (P178) was observed to bind to the ribosomes before the onset of protein synthesis during germination. Cycloheximide did not block the addition of this protein to the monoribosomes.

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A comparative study on the two classes of heterogeneous nuclear ribonucleoprotein particles separated in metrizamide density gradient, by electrophoresis of proteins and chase experiments. Evidence for two distinct subfractions of HnRNP in mammalian nuclei

Houssais

1977

Mol Biol Rep

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Heterogeneous nuclear ribonucleoprotein particles (HnRNP) were separated in metrizamide density gradients, into two fractions migrating to 1.31 g ml-1 and 1.18 g ml-1, respectively. Proteins associated with each of these fractions were analysed by SDS-acrylamide gel electrophoresis. It is shown that the whole proteins extracted from these two metrizamide fractions exhibit clearly different electrophoretic patterns: 1.31 HnRNP particles contain as major polypeptide chains molecules with molecular weights ranging from 40,000 to 65,000, while major polypeptides of 1.18 HnRNP are banding in the 30,000-40,000 molecular weight region of the gels. Both fractions contain numerous other associated polypeptide chains whose molecular weights are above 65,000. A possible kinetic relationship between these two HnRNP classes was investigated in vivo by performing chase experiments. No clear evidence for a precursor-product relationship was found. Implications arising from these structural and kinetic observations, and problems relating to nuclear maturation of pre-messenger RNA, are discussed.

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Séparation des particules ribonucléoprotéiques (Hn‐RNP) des noyaux de cellules L, en deux classes, par centrifugation isopycnique en gradients de métrizamide

Cited by 18 publications

References 21 publications

Metrizamide dissociates nuclear particles containing heterogeneous nuclear RNA

Metrizamide dissociates nuclear particles containing heterogeneous nuclear RNA

Stage-specific synthesis of proteins complexed to ribonucleoprotein particles and ribosomes in zoospores of Blastocladiella emersonii.

A comparative study on the two classes of heterogeneous nuclear ribonucleoprotein particles separated in metrizamide density gradient, by electrophoresis of proteins and chase experiments. Evidence for two distinct subfractions of HnRNP in mammalian nuclei

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