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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Secondary structure of pre-mRNA in nuclear ribonucleoprotein particles (30S-particles) was examined using fluorescent dyes: acridine orange, acriflavine and ethidium bromide. Comparison of ethidium bromide and acriflavine adsorption isotherms for RNP-particles and free RNA and a study of acridine orange dimerization on binding to RNP revealed that 70% of pre-mRNA in 30S-particles is accessible for the dye binding. Dye molecules were adsorbed on double-stranded sequences (11--12% of the total amount of RNA in 30S-particles) and on the single-stranded parts of RNA (58--59% of 30S-particles), the rest part of RNA was unaccessible for the dye binding. A method involving measurements of acriflavine fluorescence quantum yields was used for the determination of nucleotide composition of double-stranded parts of RNA in the 30S-particles. AU-nucleotide content thus obtained was approximately 50%, as was established also for free pre-mRNA. Na+ ions weaken the interaction between the protein and pre-mRNA in 30S particles and increase mobility of double-stranded parts of this nucleic acid.
Mol Biol (Mosk)
PMID:[Nuclear ribonucleoproteins containing messenger RNA. 12. Fluorescence studies of the secondary structure of pre-mRNA in nuclear RNP-particles]. 75 87

Protein of purified 30S particles analyzed by sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis is present mainly as two bands with the apparent molecular weight of 38 000 and 41 000 daltons. These bands contain not less than 90% of the total protein. When the same material is electrophoresed in the presence of urea (pH 4.5) it migrates as one homogeneous band. The procedure for isolation of free informofers in preparative scale is described. The free informofers do not contain rapidly labeled RNA and are not stable: they dissociate reversibly into protein subunits of lower molecular weights. The dissociation is concentration dependent: low concentration of protein facilitates the dissociation process. Both whole informofers and their protein subunits easily interact with free pro-mRNA yielding 30S RNP. However only the product of reconstruction with informofers is similar to native 30S particles, according to several biochemical tests. These data support the model of the structure of nuclear RNP particles according to which pro-mRNA is distributed on the surface of globular protein particles.
Mol Biol (Mosk)
PMID:[Nuclear ribonucleoprotein particles containing messenger RNA. 12. Studies of dissociation and reconstruction of 30S particles]. 75 95

A novel method of RNA fractionation based on a gradual release of the RNA molecules from ribonucleoprotein complexes has been used for the analysis of ribosomal and non-ribosomal complexes of rat liver cytoplasm. Adsorption of native ribonucleoproteins on a Celite column (occuring through only the protein moiety) followed by a consequent dissociation of RNP complexes brought about by various agents results in RNA fractionation in accordance with the tightness of the RNA-protein bonds. The cytoplasmic ribosomal and rapidly labelled non-ribosomal RNA species are separated into several fractions identified as 18S and 28S rRNA's, mRNA and messenger-like RNA. A relatively small fraction (about 10% of the total) of rRNA tenaciously bound to protein has been also revealed.
Mol Biol (Mosk)
PMID:[Study of ribonucleoprotein particles by the method of RNA chromatography on a column of nucleoprotein-celite]. 95 23

The quantitative changes of double-stranded RNA components of nuclear ribonucleo-protein particles containing pre-mRNA was investigated in the course of incubation of particles at 37 degrees C. The incubation of purified nuclear particles revealed the fragmentation of long double-stranded RNA sequences into shorter stretches. The presence of nuclear sap in the incubation mixture resulted in degradation of the double-stranded RNAs into acid soluble products. Autodegradation and/or ribonuclease treatment of nuclear RNP particles is accompanied by quantitative changes in the minor protein constituents of informofer.
Mol Biol Rep 1976 Nov
PMID:Autodegradation of pre-mRNA containing nuclear ribo-nucleoprotein particles. The effect of autodegradation on the double-stranded RNA sequences and on the protein composition of particles. 101 80

Poly(A) containing ribonucleoprotein particles were prepared from rat liver nuclei and polyribosomes. The particles have sedimentation coefficients of 14 S and 9 S, respectively. In CS2SO4 density gradients the particles banded at densities of 1.28-1.29 g cm-3. Both nuclear and polyribosomal poly(A)-RNP contain in addition to some minor polypeptides, two main polypeptides having molecular weights of 63 000 and 90 000 dalton, respectively indistinguishable from each other according to their electrophoretic mobilities.
Mol Biol Rep 1976 Nov
PMID:Nuclear and polyribosomal ribonucleoprotein particles containing poly (A) in rat liver cells. 101 81

Dense gels of E. coli 70 S ribosomes, their 50 S subunits, CM-like particles, RNP strands and their fragments, 38 S particles obtained from RNP strand folding upon addition of Mg2+ ions, and of unoriented salt-free and free rRNA sodium and magnesium salts were studied by X-ray diffraction. It was shown that under dense gel conditions RNA molecules contained in ribosomes unfolded by desalting, like all other particles considered here, have helical regions. Under these conditions free desalted RNA has no helical regions. Experimental data on X-ray scattering at medium angles were compared with the diffraction curves calculated for homogeneous prolate and oblate ellipsoids, for various ellipsoids containing a dense region or an internal cavity, and for ellipsoids containing internal periodic regions. The results indicate that the internal structure of the 50 S ribosome is periodic, i. e., its components form a periodic lattice. The lattice spacings are approximately 42 and 28 A with a 0.8g/g dry weight sample water content. When the 50 S particle water content drops below 0.2 g/g dry weight the periodic structure is disrupted. This disruption is reversible. It was shown that CM-like particles at high ionic strenght (2 M LiCl) have approximately the same internal periodicity as the 50 S particles, but in contrast they lose this periodicity at low ionic strength (10-2M tris-HCl and 5-10-3 M MgCl2).
Mol Biol 1975 Jan
PMID:An x-ray diffraction study of ribosome structure. 109 99

Nuclear 14 S RNP particles containing poly (A) from Ehrlich ascites carcinoma cells and rat liver were purified by re-sedimentation in sucrose gradients, by Cs2SO4 density gradient centrifugation and by affinity chromatography on a poly (dT)-Sepharose column. Proteins of these RNP particles were electrophoresed in urea and SDS-polyacrylamide gels. RNP particles of ascites carcinoma cells contain two main bands having molecular weights of 51 000 and 69 000 daltons, respectively, and two or three minor components.
Mol Biol Rep 1975 Mar
PMID:Protein composition of nuclear 14 S ribonucleoprotein particles containing poly (A). 112 12

Nuclear ribonucleoprotein particles were isolated from chick erythroblast nuclei. The particles were found to sediment as heterogeneous material. The major fraction of the rapidly synthesized RNP sedimented at 30 S, whereas the nuclei were found to contain a major, apparently more stable, RNP component sedimenting at about 40 S. The RNA isolated from the RNP particles was assayed for globin messenger activity in a wheat germ cell-free system. RNP sedimenting at relatively low S values (approx. 15 S) as well as RNP-particles of larger size code for globin. In addition to globin, the RNA of the particles codes also for other, not yet identified, proteins.
Mol Biol Rep 1975 Oct
PMID:Globin messenger sequences in nuclear ribonucleoprotein particles of avian erythroblasts. 119 11

The synthesis of virus-specific macromolecules was studied in the reconstituted system containing inner membrane-matrix fraction from rat liver mitochondria and infectious RNA of Venezuelian equine encephalomyelitis (VEE) virus. In a series of preliminary experiments it was shown that isolated submitochondrial fraction was completely free of interfering cytoplasmic contaminations and particularly, of cytoplasmic 80S ribosomes. VEE RNA when added to submitochondrial system caused significant stimulation of RNA and protein synthesis. These processes were resistant to actinomycin D which inhibited profoundly the synthesis of proper mitochondrial macromolecules. The stimulating effect of VEE RNA in experiments with submitochondrial system was about three times higher than that with intact mitochondria. The stimulation of 14C-amino acid incorporation increased as a function of incubation time; a certain lag-period being observed. The newly formed virus-specific RNA's and ribonucleoproteins were identified with the aid of sedimentation analysis. In particular, radioactive RNA's with sedimentation coefficients 40S and 26-18S were isolated from the incubated system. These RNA's are similar respectively to VEE genome RNA and double-stranded VEE replicative RNA. In double labelling experiments with 3H-uridine and 14C-amino acids it was shown that VEE RNA induced synthesis of ribonucleoproteins containing newly formed RNA and protein. These RNP possessed sedimentation coefficients 60-80S, 140S and 300S in sucrose gradient and buoyant densities 1.32 and 1.50 g/cm3 in cesium chloride gradients. These properties of ribonucleoproteins synthesized de novo in submitochondrial system are close to those of RNP intermediates of VEE virus reproduction in the infected cells. We concluded that viral RNA could program virus-specific synthesis in the submitochondrial system under conditions that eliminated the contribution of cytoplasmic ribosomes.
Mol Cell Biochem 1976 Jan 31
PMID:On the synthesis of viral ribonucleic acids and ribonucleoproteins in the submitochondrial system completely free of interfering cytoplasmic contaminations. 125 Feb 22

We have identified and characterized three new variants of U5 small nuclear RNA (snRNA) from HeLa cells, called U5D, U5E, and U5F. Each variant has a 2,2,7-trimethylguanosine cap and is packaged into an Sm-precipitable small nuclear ribonucleoprotein (snRNP) particle. All retain the evolutionarily invariant 9-base loop at the top of stem 1; however, numerous base changes relative to the abundant forms of U5 snRNA are present in other regions of the RNAs, including a loop that is part of the yeast U5 minimal domain required for viability and has been shown to bind a protein in HeLa extracts. U5E and U5F each constitute 7% of the total U5 population in HeLa cells and are slightly longer than the previously characterized human U5 (A, B, and C) species. U5D, which composes 5% of HeLa cell U5 snRNAs, is present in two forms: a full-length species, U5DL, and a shorter species, U5DS, which is truncated by 15 nucleotides at its 3' end and therefore resembles the short form of U5 (snR7S) in Saccharomyces cerevisiae. We have established conditions that allow specific detection of the individual U5 variants by either Northern blotting (RNA blotting) or primer extension; likewise, U5E and U5F can be specifically and completely degraded in splicing extracts by oligonucleotide-directed RNase H cleavage. All variant U5 snRNAs are assembled into functional particles, as indicated by their immunoprecipitability with anti-(U5) RNP antibodies, their incorporation into the U4/U5/U6 tri-snRNP complex, and their presence in affinity-purified spliceosomes. The higher abundance of these U5 variants in 293 cells compared with that in HeLa cells suggests possible roles in alternative splicing.
Mol Cell Biol 1992 Feb
PMID:Three novel functional variants of human U5 small nuclear RNA. 131 Jan 51


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