SEARCH · PubMed Health

Results for “RNP complex”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources

PubMed2000

A U-rich element in the 5' untranslated region is necessary for the translation of p27 mRNA.

Increased translation of p27 mRNA correlates with withdrawal of cells from the cell cycle. This raised the possibility that antimitogenic signals might mediate their effects on p27 expression by altering complexes that formed on p27 mRNA, regulating its translation. In this report, we identify a U-rich sequence in the 5' untranslated region (5'UTR) of p27 mRNA that is necessary for efficient translation in proliferating and nonproliferating cells. We show that a number of factors bind to the 5'UTR in vitro in a manner dependent on the U-rich element, and their availability in the cytosol is controlled in a growth- and cell cycle-dependent fashion. One of these factors is HuR, a protein previously implicated in mRNA stability, transport, and translation. Another is hnRNP C1 and C2, proteins implicated in mRNA processing and the translation of a specific subset of mRNAs expressed in differentiated cells. In lovastatin-treated MDA468 cells, the mobility of the associated hnRNP C1 and C2 proteins changed, and this correlated with increased p27 expression. Together, these data suggest that the U-rich dependent RNP complex on the 5'UTR may regulate the translation of p27 mRNA and may be a target of antimitogenic signals.

5' Untranslated Regions↗

PubMed1984

12 S small nuclear ribonucleoprotein-associated acidic-and pyrimidine-specific endoribonuclease from calf thymus and L5178y cells.

12 S ribonucleoprotein (RNP) particles were separated from a 45 S RNP complex (Bachmann, M., Zahn, R. K. and Müller, W. E. G. (1983) J. Biol. Chem. 258, 7033-7040) isolated from calf thymus and L5178y cells. The particles were determined to be associated with an acidic endoribonuclease (pI 4.1; pH optimum 6.2). the enzyme requires Mg2+ and is sensitively inhibited by higher NaCl concentrations. The nuclease specifically degrades poly(U) and poly(C) in an endonucleolytic manner; the end-products are 3'-UMP (85%) and 2',3'-cyclic UMP (12%). Poly(A) strongly inhibits the pI 4.1 endoribonuclease activity. The Michaelis constant (for poly(U)) was determined as 82 microM and the maximal reaction velocity was 0.54 mumol/microgram per h. The endoribonuclease is distinguished from the known pyrimidine-specific ribonucleases (pancreatic ribonuclease and endoribonuclease VII) by further criteria, e.g., resistance to thiol reagents, inhibition by EDTA, Mg2+ requirement, pI and pH optimum. Using the techniques of counterimmunoelectrophoresis and immunoaffinity column chromatography it was shown that the pI 4.1 endoribonuclease-associated 12 S RNP particles display antigenicity to anti-Sm and anti-(U1)-RNP antibodies. An RNA component, isolated from the 12 S-45 S hypercomplex, was identified as U1-snRNA.

Animals↗

PubMed2001

The heterogeneous nuclear ribonucleoproteins I and K interact with a subset of the ro ribonucleoprotein-associated Y RNAs in vitro and in vivo.

The hY RNAs are a group of four small cytoplasmic RNAs of unknown function that are stably associated with at least two proteins, Ro60 and La, to form Ro ribonucleoprotein complexes. Here we show that the heterogeneous nuclear ribonucleoproteins (hnRNP) I and K are able to associate with a subset of hY RNAs in vitro and demonstrate these interactions to occur also in vivo in a yeast three-hybrid system. Experiments performed in vitro and in vivo with deletion mutants of hY1 RNA revealed its pyrimidine-rich central loop to be involved in interactions with both hnRNP I and K and clearly showed their binding sites to be different from the Ro60 binding site. Both hY1 and hY3 RNAs coprecipitated with hnRNP I in immunoprecipitation experiments performed with HeLa S100 extracts and cell extracts from COS-1 cells transiently transfected with VSV-G-tagged hnRNP-I, respectively. Furthermore, both anti-Ro60 and anti-La antibodies coprecipitated hnRNP I, whereas coprecipitation of hnRNP K was not observed. Taken together, these data strongly suggest that hnRNP I is a stable component of a subpopulation of Ro RNPs, whereas hnRNP K may be transiently bound or interact only with (rare) Y RNAs that are devoid of Ro60 and La. Given that functions related to translation regulation have been assigned to both proteins and also to La, our findings may provide novel clues toward understanding the role of Y RNAs and their respective RNP complexes.

Animals↗

PubMed1991

The 5' end domain of U2 snRNA is required to establish the interaction of U2 snRNP with U2 auxiliary factor(s) during mammalian spliceosome assembly.

Stable association of U2 snRNP with the branchpoint sequence of mammalian pre-mRNAs requires binding of a non-snRNP protein to the polypyrimidine tract. In order to determine how U2 snRNP contacts this protein, we have used an RNA containing the consensus 5' and the (Py)n-AG 3' splice sites but lacking the branchpoint sequence so as to prevent direct U2 snRNA base pairing to the branchpoint. Different approaches including electrophoretic separation of RNP complexes formed in nuclear extracts, RNase T1 protection immunoprecipitation assays with antibodies against snRNPs and UV cross-linking experiments coupled to immunoprecipitations allowed us to demonstrate that at least three splicing factors contact this RNA at 0 degree C without ATP. As expected, U1 snRNP interacts with the region comprising the 5' splice site. A protein of approximately 65,000 molecular weight recognizes the RNA specifically at the 5' boundary of the polypyrimidine tract. It could be either the U2 auxiliary factor (U2AF) (Zamore and Green (1989) PNAS 86, 9243-9247), the polypyrimidine tract binding protein (pPTB) (Garcia-Blanco et al. (1989) Genes and Dev. 3, 1874-1886) or a mixture of both. U2 snRNP also contacts the RNA in a way depending on p65 binding, thereby further arguing that the latter may correspond to the previously characterized U2AF and pPTB. Cleavage of U2 snRNA sequence by a complementary oligonucleotide and RNase H led us to conclude that the 5' terminus of U2 snRNA is required to ensure the contact between U2 snRNP and p65 bound to the RNA. More importantly, this conclusion can be extended to authentic pre-mRNAs. When we have used a human beta-globin pre-mRNA instead of the above artificial substrate, RNA bound p65 became precipitable by anti-(U2) RNP and anti-Sm antibodies except when the 5' end of U2 snRNA was selectively cleaved.

Animals↗

PubMed2002

Restricted specificity of intermolecular spreading to endogenous La (SS-B) and 60 kDa Ro (SS-A) in experimental autoimmunity.

Intermolecular spreading of humoral autoimmunity to different components of the Ro (SS-A) and La (SS-B) ribonucleoprotein (RNP) complex has been reported following immunization with a single component of the complex. Although the immune response to the immunizing antigen is polyclonal and diversified, little is known about the specificity of the recruited autoimmune responses to the endogenous Ro and La antigens which drive B-cell spreading. To determine the specificity of intermolecular spreading to La, we examined sera from 52 kDa Ro (Ro52)- and 60 kDa Ro (Ro60)-immunized C3H/HeJ mice for reactivity with recombinant fragments spanning endogenous mouse (m)La by enzyme-linked immunosorbent assay (ELISA) and immunoblotting. Sera from mice primed and boosted with recombinant Ro52 and Ro60 showed reactivity restricted to the COOH-terminal fragment of mLa (aa361-415). The recruited anti-La response was species-specific, cross-reacting weakly with the corresponding region on the human La molecule, and was abrogated by the preabsorption of the Ro-immune sera with mLa 361-415. Analogous experiments using recombinant mRo60 fragments spanning the mRo60 molecule revealed a similar pattern of oligoclonality in the specificity of anti-Ro60 autoimmunity following active immunization with La and Ro52. These results suggest that intermolecular-intrastructural T-B help is limiting in this model, and reveal unsuspected immunodominance of selected Ro-La epitopes in the spreading of the autoantibody response to these structures. The focusing of the recruited autoantibody response to these COOH-terminal regions of the Ro and La polypeptides may also reflect the surface accessibility of these regions in La-Ro RNP.

Animals↗

PubMed2002

Human Ro60 (SSA2) genomic organization and sequence alterations, examined in cutaneous lupus erythematosus.

BACKGROUND: The Ro 60 kDa protein (Ro60 or SSA2) is the major component of the Ro ribonucleoprotein (Ro RNP) complex, to which an immune response is a specific feature of several autoimmune diseases. The genomic organization and any sequence variation within the DNA encoding Ro60 are unknown. OBJECTIVES: To characterize the Ro60 gene structure and to assess whether any sequence alterations might be associated with serum anti-Ro antibody in subacute cutaneous lupus erythematosus (SCLE), thus potentially providing new insight into disease pathogenesis. METHODS: The cDNA sequence for Ro60 was obtained from the NCBI database and used for a BLAST search for a clone containing the entire genomic sequence. The intron-exon borders were confirmed by designing intronic primer pairs to flank each exon, which were then used to amplify genomic DNA for automated sequencing from 36 caucasian patients with SCLE (anti-Ro positive) and 49 with discoid LE (DLE, anti-Ro negative), in addition to 36 healthy caucasian controls. RESULTS: Heteroduplex analysis of polymerase chain reaction (PCR) products from patients and controls spanning all Ro60 exons (1-8) revealed a common bandshift in the PCR products spanning exon 7. Sequencing of the corresponding PCR products demonstrated an A > G substitution at nucleotide position 1318-7, within the consensus acceptor splice site of exon 7 (GenBank XM001901). The allele frequencies were major allele A (0.71) and minor allele G (0.29) in 72 control chromosomes, with no significant differences found between SCLE patients, DLE patients and controls. CONCLUSIONS: The genomic organization of the DNA encoding the Ro60 protein is described, including a common polymorphism within the consensus acceptor splice site of exon 7. Our delineation of a strategy for the genomic amplification of Ro60 forms a basis for further examination of the pathological functions of the Ro RNP in autoimmune disease.

Antibodies, Antinuclear↗

PubMed2002

Subcellular redistribution of la/SSB autoantigen during physiologic apoptosis in the fetal mouse heart and conduction system: a clue to the pathogenesis of congenital heart block.

OBJECTIVE: In isolated congenital heart block, the mechanism by which maternal autoantibodies target the intracellular components of the Ro/La RNP complex is unclear. Previous studies have demonstrated that cultured fetal cardiac myocytes rendered apoptotic bind antibodies to 48-kd La/SSB. This study further investigated the subcellular distribution of the La antigen during apoptosis in the fetal mouse heart and conduction system. METHODS: The atrioventricular (AV) node, AV bundle, and sinoatrial (SA) node were identified in serial sections prepared from paraffin blocks of normal mouse fetuses on days 15, 17, and 19 of gestation. Apoptosis was detected by TUNEL assay. Under confocal microscopy, fluorescent labeling of fragmented DNA in apoptotic cells was assessed by TUNEL, and La protein localization was visualized simultaneously using a murine monoclonal antibody or affinity-purified human polyclonal anti-La antibodies. RESULTS: Apoptotic cells were detected in and at the periphery of the AV and SA nodes as well as in the fetal heart valve insertions and working myocardium. In contrast, no apoptosis was detected in the adult heart AV node or surrounding myocardium. As expected, the La antigen was predominantly immunolocalized to the nucleus in nonapoptotic cells. However, apoptotic cells showed a marked reduction of nuclear La and redistribution of La to the cytoplasm. High-resolution confocal microscopy revealed that in cells that had undergone apoptosis, La antigen asymmetrically clustered near the surface of TUNEL-positive nuclei and apoptotic bodies. CONCLUSION: These data provide the first in vivo demonstration of the subcellular translocation of La autoantigen during apoptosis in the fetal heart and the conduction system under physiologic conditions. This observation supports the hypothesis that subcellular redistribution of La in the normally developing heart facilitates the binding of cognate maternal antibodies and subsequent tissue damage.

Animals↗

PubMed1986

Complement-activating abilities of defined antinuclear antibodies.

A complement-fixing immunofluorescence assay on HEp-2 cells was used to assess the ability of various antinuclear antibodies (ANA) to activate complement. Sera which contained only specific antibodies to nuclear RNP, SS-B/La, centromere, Sm antigen, double-stranded DNA, and/or nuclear histone were selected. Relative abilities of various ANA to activate complement were determined from the ratio of titers of C3, C4, or properdin-fixing ANA to the IgG ANA titers. Nuclear RNP-anti-RNP complexes activated and deposited significantly more complement C3 than other ANA (P less than 0.02). Antibodies to SS-B/La, centromere, and Sm activated more complement than anti-DNA or antihistone (P less than 0.02). Antihistone antibodies activated the least complement. These studies demonstrate that different ANA have significantly different orders of complement-activating capabilities when bound to their respective nuclear antigens.

Antibodies, Antinuclear↗

PubMed1994

Subunits of the Saccharomyces cerevisiae signal recognition particle required for its functional expression.

The signal recognition particle (SRP) is an evolutionarily conserved ribonucleoprotein (RNP) complex that functions in protein targeting to the endoplasmic reticulum (ER) membrane. Only two protein subunits of the SRP, Srp54p and Sec65p, and the RNA subunit, scR1, were previously known in the yeast Saccharomyces cerevisiae. Purification of yeast SRP by immunoaffinity chromatography revealed five additional proteins. Amino acid sequencing and cloning of the genes encoding four of these proteins demonstrated that the yeast SRP contains homologs (termed Srp14p, Srp68p and Srp72p) of the SRP14, SRP68 and SRP72 subunits found in mammalian SRP. The yeast SRP also contains a 21 kDa protein (termed Srp21p) that is not homologous to any protein in mammalian SRP. An additional 7 kDa protein may correspond to the mammalian SRP9. Disruption of any one of the four genes encoding the newly identified SRP proteins results in slow cell growth and inefficient protein translocation across the ER membrane. These phenotypes are indistinguishable from those resulting from the disruption of genes encoding SRP components identified previously. These data indicate that a lack of any of the analyzed SRP components results in loss of SRP function. ScR1 RNA and SRP proteins are at reduced levels in cells lacking any one of the newly identified proteins. In contrast, SRP components are present at near wild type levels and SRP subparticles are present in cells lacking either Srp54p or Sec65p. Thus Srp14p, Srp21p, Srp68p and Srp72p, but not Sec65p or Srp54p, are required for stable expression of the yeast SRP.

Amino Acid Sequence↗

PubMed1995

Mitochondrial import of a cytoplasmic lysine-tRNA in yeast is mediated by cooperation of cytoplasmic and mitochondrial lysyl-tRNA synthetases.

Cytoplasmic tRNA(Lys)CUU is the only nuclear-encoded tRNA of Saccharomyces cerevisiae found to be associated with mitochondria. Selective import of this tRNA into isolated organelles requires cytoplasmic factors. Here we identify two of these factors as the cytoplasmic and mitochondrial lysyl-tRNA synthetases. The cytoplasmic enzyme is obligatory for in vitro import of the deacylated, but not of the aminoacylated tRNA. We thus infer that it is needed for aminoacylation of the tRNA, which is a prerequisite for its import. The mitochondrial synthetase, which cannot aminoacylate tRN(Lys)CUU, is required for import of both aminoacylated and deacylated forms. Its depletion leads to a total arrest of tRNA import, in vitro and in vivo. The mitochondrial lysyl-tRNA synthetase is able to form specific and stable RNP complexes with the amino-acylated tRNA. Furthermore, an N-terminal truncated form of the synthetase which cannot be targeted into mitochondria is unable to direct the import of the tRNA. We therefore hypothesize that the cytosolic precursor form of the mitochondrial synthetase has a carrier function for translocation of the tRNA across the mitochondrial membranes. However, cooperation of the two synthetases is not sufficient to direct tRNA import, suggesting the need of additional factor(s).

Acylation↗

PubMed1996

Unmasking mRNA in clam oocytes: role of phosphorylation of a 3' UTR masking element-binding protein at fertilization.

During meiotic maturation or after fertilization of invertebrate and vertebrate oocytes, many of the quiescent stored mRNAs are recruited into polysomes. In the clam, Spisula solidissima, such masked messages include the abundant mRNAs encoding cyclin A and the small subunit of ribonucleotide reductase. We have previously shown that mRNA-specific unmasking of these two messages can be achieved in vitro, in oocyte cell-free extracts, by the addition of antisense RNAs corresponding to a fairly short (130-140 nucleotides) segment in their cognate 3' untranslated regions. We postulated that the antisense RNAs prevented the binding of a masking repressor protein (Standart et al., 1990). Here we report UV-crosslinking and gel retardation studies which show that the masking portions of the translationally regulated mRNAs bind an oocyte protein of 82 kDa (p82), which is phosphorylated after fertilization. This modification was accompanied by altered RNP complex formation in gel retardation assays. These changes presumably reflect the activation of translation of the masked mRNAs. The role of p82 phosphorylation in maternal mRNA unmasking was assessed in a novel in vitro activation system developed from clam oocytes, based upon the natural rise in pH which accompanies fertilization. Concomitant with mRNA unmasking, several kinases, including cdc2 and MAP kinases were activated in this system, as was p82 phosphorylation. Inhibitors of serine/threonine kinases, including 6-DMAP, staurosporine, and H7 inhibited p82 phosphorylation, whereas inhibitors of tyrosine kinases, protein kinase C, cAMP-dependent protein kinase, and p70s6k did not prevent this modification. A specific inhibitor of cdc2 kinase, p27Kip1, prevented p82 phosphorylation and translational activation, strongly suggesting that p82 modification is required for unmasking.

Amino Acid Sequence↗

PubMed1995

Contributions of multiple basic amino acids in the C-terminal region of yeast ribosomal protein L1 to 5 S rRNA binding and 60 S ribosome stability.

Previous studies suggest that the C-terminal region of ribosomal protein L1 from Saccharomyces cerevisiae is important for its interaction with the 5 S rRNA molecule. Within this region are several highly conserved basic amino acids including Lys276, Lys279, Lys289, Arg282, Arg285. To examine potential contributions of these amino acids to RNA-protein interaction and ribosomal assembly, effects of substitutions of these residues by methionine either individually or in combinations were examined. A methionine substitution of any one of the lysine residues did not significantly affect RNA binding in vitro. The mutant RNPs were as stable as the wild-type RNP. Yeast transformants expressing these mutant proteins grew at the same rate as the wild-type. However, mutant proteins containing substitutions of any two of these basic amino acids bound RNA weakly. The resultant RNPs were significantly less stable than the wild-type. Whereas cells expressing mutant L1 with a single substitution at 289 was not lethal, cells expressing mutant L1 with any double substitutions involving Lys289 as one of the substituted amino acids were lethal. These data suggest that Lys289 plays a key role in the binding of ribosomal protein L1 to 5 S rRNA. The other basic residues, particularly Arg282, and Arg285, in this region also contribute to RNA binding. These residues are predicted to locate on the same side of an alpha helix. We would like to propose a structural model for the yeast RNP that involves multiple contact sites located on one side of the helix in the C terminus of the protein and the 5 S rRNA. These basic amino acids also participate, directly or indirectly, in the interaction of the RNP complex with other components of the 60 S ribosomal subunit.

Amino Acid Sequence↗

PubMed1999

Simultaneous localization of transcription and early processing markers allows dissection of functional domains in the plant cell nucleolus.

Nucleolar transcription in isolated onion cell nuclei was visualized, after Br-UTP incorporation, under the conventional fluorescence microscope, the confocal microscope, and the transmission electron microscope. The confocal microscopy study of transcription was combined with immunodetection of fibrillarin, a component of the RNP complex involved in the early processing of pre-rRNA. Superposition of transcription and fibrillarin images from the same optical section showed some small "black holes" in the nucleolus, around which a lateral and radial differentiation of labeling was observed: laterally, zones corresponding to transcription labeling alternated with zones of fibrillarin labeling; radially, areas of transcription gradually became areas of colocalization of transcription and fibrillarin, and, further outward, of fibrillarin alone, which occupied the major part of the labeled nucleolar area. Three-dimensional reconstruction of the nucleolar transcription labeling, from confocal optical sections, showed clusters of foci arranged around an area of low or no labeling. Thin labeled extensions, connecting single foci, were observed. Visualization of transcription at the ultrastructural level identified the black holes as fibrillar centers, in view of their size and the absence of labeling in them. In fact, most of the labeling was observed in discrete areas of the dense fibrillar component, near fibrillar centers, including the transition area between these two components. This observation was supported by a quantitative study. Otherwise, the outline of fibrillar centers did not appear entirely surrounded by particles, and a minor proportion of particles was detected dispersed throughout the dense fibrillar component. As a complementary study, the transcription factor upstream binding factor (UBF) and the protein NopA64, a plant nucleolin homologue, were immunolocalized. Small foci of UBF localization alone and other foci in which the two protein markers overlapped were observed. The outer areas of the nucleolus showed the exclusive presence of NopA64. Under the electron microscope, UBF labeling, quantitatively assessed, appeared as clusters of particles, most of them surrounding fibrillar centers. A graphic model is presented to give a molecular interpretation of these data.

Bromodeoxyuridine↗

PubMed1995

Polymerase activity of in vitro mutated rabies virus L protein.

The large (L) protein of nonsegmented negative-strand RNA viruses is the multifunctional catalytic component of the viral ribonucleoprotein (RNP) complex. To address the role of conserved rabies virus (RV) L protein sequences predicted to be involved in RNA polymerase activity, a reverse genetics approach was applied that allows intracellular reconstitution of transcriptionally active RV RNPs from plasmid-encoded proteins. Artificial RV model genomes encoding bacterial chloramphenicol acetyltransferase or firefly luciferase was used to determine the polymerase activity of a series of 23 RV L proteins mutated in the highly conserved C motif of the proposed polymerase module. All constructs with mutations of the GDN core sequence of motif C, which is proposed to be a variant of the catalytical XDD residues of RNA polymerase and reverse transcriptases, failed to express the reporter genes. In addition, the identity of the upstream residues AQ was crucial for maintenance of polymerase activity. Several conservative and nonconservative mutations introduced into the three amino acids QVL located downstream of the GDN core resulted in reduced polymerase activities and expression of luciferase in the range 0.4 to 92% compared to the parental L protein.

Amino Acid Sequence↗

PubMed2004

Reverse genetics of mononegavirales.

"Reverse genetics" or de novo synthesis of nonsegmented negative-sense RNA viruses (Mononegavirales) from cloned cDNA has become a reliable technique to study this group of medically important viruses. Since the first generation of a negative-sense RNA virus entirely from cDNA in 1994, reverse genetics systems have been established for members of most genera of the Rhabdo-, Paramyxo-, and Filoviridae families. These systems are based on intracellular transcription of viral full-length RNAs and simultaneous expression of viral proteins required to form the typical viral ribonucleoprotein complex (RNP). These systems are powerful tools to study all aspects of the virus life cycle as well as the roles of virus proteins in virus-host interplay and pathogenicity. In addition, recombinant viruses can be designed to have specific properties that make them attractive as biotechnological tools and live vaccines.

Animals↗

PubMed1996

Strukturdifferenzierungen in Y-chromosom von Drosophila hydei: the unique morphology of the Y chromosomal lampbrush loops Threads results from 'coaxial shells' formed by different satellite-specific subregions within megabase-sized transcripts.

The results of pulsed-field gel electrophoresis (PFGE) analysis and two-colour transcript fluorescence in situ hybridization (FISH) for the three Threads-specific DNA satellites YLII, YLI and rally are in support of long-range clustering of these sequence families within the subterminal region on the long arm of the Y chromosome of Drosophila hydei. On the basis of the linear arrangement of at least four extended clusters of satellite-specific sequences, the loop morphology of wild-type and several mutant Threads can be explained by assumption of a single Threads-specific transcription unit comprising about 5.1 Mb of repetitive DNA located between the Pseudonucleolus and the Nucleolus organizer. Transcription is unidirectional from the Pseudonucleolus towards the terminally located Nucleolus organizer. Transcripts most likely start in front of or within the 3.2 Mb region of YLII-related sequences, pass through subsequent blocks of 1.2 and 0.3 Mb of YLI- and rally-related sequences, respectively, and cease within the region of a smaller block of YLI-related repeats. The megabase-sized transcripts remain physically linked to the DNA axis and their extended satellite-specific regions form coaxial clouds or shells around the central DNA axis. In this way each cluster of earlier-transcribed sequences generates a cloud or shell on top of the later-transcribed ones. According to this model of 'satellite-specific coaxial shells' the tube-like morphology and other peculiarities of the Y chromosomal lampbrush loops Threads can be explained as a result of satellite-specific RNA superstructures and/or formation of extended ribonucleoprotein (RNP) complexes between clusters of satellite-specific transcripts and specific proteins. On the basis of this model the specific morphology of several Threads mutants can be interpreted as the result of large interstitial or terminal deletions that alter the total length of the Threads-specific transcription unit without exerting other major effects on principal features of the transcription process along the Threads.

Animals↗

PubMed1983

Isolation and characterization of a 7 S RNP particle from mature Xenopus laevis oocytes.

Mature oocytes of Xenopus laevis contain a 7 S RNP particle consisting of two components, ribosomal 5 S RNA and a protein of Mr approximately 45000. The structure of the free 5 S rRNA and the 7 S RNP complex has been studied by diethylpyrocarbonate modification of adenines. A74, A77, A90, A100, A101 and A103 of the 5 S rRNA are protected upon association of the protein.

Animals↗

PubMed1989

Prosomes discriminate between mRNA of adenovirus-infected and uninfected HeLa cells.

Prosomes are small cytoplasmic RNP complexes associated with repressed mRNA. In in vitro translation, they discriminate between the mRNA of adenovirus-infected HeLa cells and those of uninfected cells grown under normal conditions. Prosomes as well as their RNA constituents interact much more strongly with poly(A)+ mRNA of infected cells and inhibit their translation in vitro preferentially. A possible role of prosomes in the differential regulation of translation is discussed.

Adenoviridae↗