Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “RIBOSOMES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 919 records · Page 51Linked to original sources
PubMed1984

The nucleotide sequence of a rat 18 S ribosomal ribonucleic acid gene and a proposal for the secondary structure of 18 S ribosomal ribonucleic acid.

The nucleotide sequence of a rat 18 S rRNA gene was determined. The 18 S rRNA encoded in the gene contains 1874 nucleotides, and the molecular weight estimated from the sequence is 6.09 X 10(5). The sequences of rat and Xenopus laevis 18 S rRNAs are very similar; the only differences of consequence are the insertions between nucleotides 197 and 206 and between 258 and 279 of the rat nucleic acid of sequences rich in guanine and cytosine. A proposal is presented for the secondary structure of rat 18 S rRNA based on a comparison with the sequences of 17 other small ribosomal subunit RNAs. While the primary sequences of rat and eubacterial RNAs are different, the deduced secondary structures are remarkably similar.

Animals↗
PubMed1983

[Study of the ribosome mRNA-binding region during different stages of translation. I. Functional activity of mRNA analogs, AUGU6 and its benzylidene derivatives, in ribosome-dependent protein synthesis].

Hexaribouridylic acid, prepared by digestion of poly(U) with cobra venom endonuclease, and trinucleotide AUG synthesized chemically by triester approach were joined by RNA-ligase to yield a nonaribonucleotide AUGU6 bearing the initiation codon at its 5'-terminus. 2',3'-O-(4-[N-(2-chloro(or hydroxy) ethyl-N-Methylamino])- benzylidene residues were introduced at the 3'-terminus of oligonucleotide AUGU6 and its benzylidene derivatives AUGU6CHRCl or AUGU6CHROH were obtained. The mRNA analogs synthesized were tested for their template activity in the formation of 70S initiation complex. AUGU6, AUGU6CHRC1 and AUGU6CHROH were shown to stimulate factor-dependent binding of fMet-tRNA to ribosomes. The effect of benzylidene fragment on the template activity of AUGU6CHROH in the course of translation process was studied. It was shown that AUGU6CHROH stimulates synthesis of di- and tripeptides with the same efficiency as AUGU6.

Benzylidene Compounds↗
PubMed1997

Exact determination of UV-induced crosslinks in 16S ribosomal RNA in 30S ribosomal subunits.

Escherichia coli 30S ribosomal subunits were UV-irradiated to induce intramolecular crosslinks in the 16S rRNA. Intact 16S rRNA was purified and subjected to gel electrophoresis, under denaturing conditions, to separate molecules on the basis of the crosslinked loop size. Molecules separated this way were enriched for specific crosslinks and could be analyzed by the reverse transcription arrest assay to determine exact crosslinking sites. Thirteen crosslinking sites have been identified at single nucleotide resolution. Of these, eight are within or adjacent to secondary structure elements: one of these (C582 x G760) involves an interaction between nucleotides within an interior loop, one (C1402 x X1501) involves an interaction between nucleosides in adjacent base pairs, and the others involve interactions between nucleotides that are within junction regions (A441 x G494, U562 x U884, C934 x U1345, and U991 x U1212) or are interactions between nucleotides (C54 x A353 and U1052 x C1200) that somehow cross known base pairs. Five other crosslinks connect sites distant in the secondary structure and provide global constraints for the arrangement of RNA regions within RNA domains I and II (U244 x G894, G894 x A1468, C967 x C1400) and within domain III (U1126 x C1281 and A1093 x G1182). These crosslinks, known at single-nucleotide resolution, are useful in the prediction of local RNA regions, as well as the global structure.

Base Sequence↗
PubMed1991

Depletion of U3 small nucleolar RNA inhibits cleavage in the 5' external transcribed spacer of yeast pre-ribosomal RNA and impairs formation of 18S ribosomal RNA.

Multiple processing events are required to convert a single eukaryotic pre-ribosomal RNA (pre-rRNA) into mature 18S (small subunit), 5.8S and 25-28S (large subunit) rRNAs. We have asked whether U3 small nucleolar RNA is required for pre-rRNA processing in vivo by depleting Saccharomyces cerevisiae of U3 by conditional repression of U3 synthesis. The resulting pattern of accumulation and depletion of specific pre-rRNAs indicates that U3 is required for multiple events leading to the maturation of 18S rRNA. These include an initial cleavage within the 5' external transcribed spacer, resembling the U3 dependent initial processing event of mammalian pre-rRNA. Formation of large subunit rRNAs is unaffected by U3 depletion. The similarity between the effects of U3 depletion and depletion of U14 small nucleolar RNA and the nucleolar protein fibrillarin (NOP1) suggests that these could be components of a single highly conserved processing complex.

Animals↗
PubMed2000

Ribosomal protein S19 gene mutations in patients with diamond-blackfan anemia and identification of ribosomal protein S19 pseudogenes.

Diamond-Blackfan anemia (DBA) is a rare congenital pure red cell hypoplasia characterized by a selective defect of erythropoiesis with a normochromic macrocytic anemia and reticulocytopenia often accompanied by various congenital anomalies. The critical region responsible for the pathogenesis of DBA has been mapped in some patients to chromosome 19q13.2 (P Gustavsson, E Garelli, N Draptchinskaia, et al. Am. J. Hum. Genet. 63:1388-1395, 1998) and the gene encoding ribosomal protein S19 (RPS19) is believed to be the candidate gene. Here we present molecular analysis of the RPS19 gene in DBA patients from the Czech National DBA Registry. We found that the RPS19 gene was mutated in 25% (5/20) of DBA patients (insertion, deletion, and point mutations, but no nonsense or splice site mutations). Point mutations were localized to hot spots defined by Willig (TN Willig, N Draptchinskaia, I Dianzani, et al. Blood 94:4294-4306, 1999). Moreover, we describe two processed RPS19 pseudogenes, which were not expressed. Possible models of the DBA pathogenesis in the view of RPS19 mutations are discussed.

Adolescent↗
PubMed1996

Characterization of a maize ribosomal P2 protein cDNA and phylogenetic analysis of the P1/P2 family of ribosomal proteins.

The nucleotide sequence of a full-length ribosomal P2 protein cDNA from maize was determined and used for a sequence comparison with the P2 and P1 proteins from other organisms. The integration of these data into a phylogenetic tree shows that the P proteins separated into the subspecies P1 and P2 before the eukaryotic kingdoms including plants developed from their ancestor.

Base Sequence↗
PubMed1976

The ribosomes of Drosophila. IV. Electrophoretic identify among ribosomal subunit proteins from wild type and mutant D. melanogaster and D. simulans.

One- and two-dimensional gel electrophoresis was employed to characterize and compare ribosomal subunit proteins from wild-type D. melanogaster and several mutants, including suppressor-of-forked and four X-linked cold sensitive lethals. The sibling species D. simulans was also studied. We found the electropherogram patterns indistinguishable in all cases.

Animals↗
PubMed1978

Control of ribosomal RNA synthesis in Escherichia coli. IV. Frequency of transcription of ribosomal RNA genes as a function of growth rate.

Nucleoids were isolated from Escherichia coli B/r cells in steady-stage growth at different rates. The number of RNA chains growing on each nucleoid was estimated from the amount and size of RNAs synthesized by endogenous RNA polymerase. This figure represents the number of RNA polymerase molecules that are functioning in transcription and thus serves to indicate the frequency of transcription in the cells. With an increase in the growth rate from 0.27 to 1.73 (h-1), (a) the number of total RNA chains per genome increases from about 252 to 838, (b) the number of ribosomal RNA (rRNA) chains per genome increases as a function of the second power of the growth rate from about 19 to 255, and (c) the number of non-rRNA chains per genome increases linearly from about 233 to 538.

DNA-Directed RNA Polymerases↗
PubMed1975

Cooperative control of translation fidelity by ribosomal proteins in Escherichia coli. I. Properties of ribosomal mutants whose resistance to neamine is the cumulative effect of two distinct mutations.

Two spontaneous mutants of Escherichia coli strain KMBL-146 selected for resistance to the aminoglycoside antibiotic neamine show severe restriction of amber suppressors in vivo. Purified ribosomes from the mutant strains exhibit low neamine-induced misreading in vitro and a decreased affinity for the related antibiotic streptomycin. Biochemical analysis shows that the mutants each have two modified 30S ribosmal proteins, S12 and S5. In agreement with these results, genetic analysis shows that two mutations are present, neither of which confers resistance to neamine by itself; the mutation located in gene rpxL (the structural gene for protein S12) confers streptomycin dependence but this dependence is suppressed in the presence of the second mutation, located in gene rpxE (the structural gene for protein S5).

Chromosome Mapping↗
PubMed1977

Control of ribosomal RNA synthesis in Escherichia coli. III. Cytoplasmic factors for ribosomal RNA synthesis.

The ribosomal RNA synthesis in a cell-free system containing the nucleoids and the cytoplasmic fraction prepared from Escherichia coli cells has been investigated. The addition of the "4S" fraction from the cytoplasm to the isolated nucleoids induces RNA synthesis by a new chain initiation. In this system a preferential initiation or rRNA chains occurs. The experimental results suggest that the 4S fraction contains at least two activities, one for releasing RNA-polymerases from the nucleoids, and another for the frequent initiation of rRNA chains. No restriction of the rRNA synthesis has been observed in the nucleoids and the 4S fraction from the amino acid-starved rel+ cells. The rRNA synthesized in the above system is detected at about 23S and 16S rRNA regions.

Cell-Free System↗
PubMed1975

Proteinchemical studies on ribosomal proteins S4 and S12 from ram (ribosomal ambiguity) mutants of Escherichia coli.

Proteins S4 and S12 were isolated from ribosomes of three mutants of Escherichia coli in which dependence on streptomycin caused by alteration in protein S12 is suppressed by an altered protein S4. Proteinchemical studies on the mutant proteins gave the following results: Proteins S12 from all three mutants differ from S12 of the wild type by the replacement of proline to leucine in peptide T15. In all mutant S4 proteins a replacement og glutamine to leucine at amino acid position 53 was found. In addition to this replacement at position 53 a glutamic acid residue at position 199 near the C-terminus was deleted in one of the three mutants. However, this deletion is not necessary for the ability of the mutant S4 protein to suppress dependence on streptomycin. The results support the hypothesis that ram mutants and "revertants" from streptomycin dependence to independence belong to the same class although they were isolated by different selection procedures.

Amino Acids↗
PubMed1985

Gene rpmF for ribosomal protein L32 and gene rimJ for a ribosomal protein acetylating enzyme are located near pyrC (23.4 min) in Escherichia coli.

An Escherichia coli mutant harbouring altered ribosomal protein L32 has been isolated and genetically characterized. The mutation leading to this alteration (rpmF) and the temperature-sensitive mutation (ts-1517) present in the same strain were found to map near pyrC (23.4 min), being cotransducible not only with pyrC but also with fabD, flaT and purB in P1 phage mediated transductions. Furthermore, we found that the gene rimJ, which encodes an enzyme that acetylates the N-terminal alanine of protein S5 and the temperature-sensitive mutation, ts-386, present in the rimJ mutant strain (Cumberlidge and Isono 1979) also mapped in this region. Thus, the order of genes is deduced to be: ts-386-pyrC-ts-1517-rimJ-flaT-fabD-rpmF-purB+ ++.

Acetyltransferases↗
PubMed1988

Nucleotide sequence and determination of the extremities of the 26S ribosomal RNA gene in wheat mitochondria: evidence for sequence rearrangements in the ribosomal genes of higher plants.

The nucleotide sequence of the wheat mitochondrial 26S ribosomal RNA gene and flanking regions was determined and compared with mitochondrial 26S rRNA genes from maize and Oenothera. All three genes exhibit a high degree of homology except within two variable regions. When the plant mitochondrial 26S rRNA genes are compared with Escherichia coli 23S rRNA and chloroplast 23S and 4.5S rRNA genes, a third variable region is apparent close to the 3' end of the gene. The 5' and 3' ends of the wheat mitochondrial gene were determined by S1 nuclease mapping. Computer analysis of the wheat mitochondrial gene revealed several small sequences present either in the 5' region of the 26S rRNA gene or in the 18S rRNA gene.

Base Sequence↗
PubMed1984

Ribosomal RNA contents of maize genotypes with different ribosomal RNA gene numbers.

Ribosomal RNA (rRNA) contents were determined in 16 maize genotypes whose individual rRNA gene numbers varied from 5000 to 23,000 per 2C nucleus. Analytical polyacrylamide gel electrophoresis of total RNA showed that no obvious relation existed between rRNA gene number and rRNA content. Only two of nine common inbred lines contained more rRNA than W-23, the inbred with the lowest rRNA gene number. Two of four lines with altered protein content (due to long-term experimental selection) had rRNA contents significantly reduced from those of W-23. A line with an apparent duplication of the nucleolus organizer region of chromosome 6 (called 2-NOR) was expected to possess an elevated quantity of rRNA because it possesses a larger nucleolus; however, we produced a 2-NOR isogenic version and found no difference in rRNA content. The rRNA genes in maize are distributed throughout the NOR-heterochromatin and the NOR-secondary constriction portions of the NOR. The absence of an obvious correlation between rRNA gene number and cellular rRNA content may reflect the presence of a large number of rRNA genes in an inactive state, at least during the stage of growth examined in these experiments.

Gene Expression Regulation↗
PubMed1975

Free and membrane-bound ribosomes. II. Two-dimensional gel electrophoresis of proteins from free and membrane-bound rabbit reticulocyte ribosomes.

Free and membrane-bound polysomes were isolated from rabbit reticulocytes. The membrane-bound polysomes were liberated form the membrane with deoxycholate. Monosomes were prepared from the two types of polysomes by incubation with puromycin. The ribosomal proteins were extracted and analyzed by two-dimensional gel electrophoresis. Two proteins of the large subunit, L11 and L17 present in the free monosomes were not found in the membrane-bound monosomes. On the other hand, four additional spots were found in the protein pattern of the membrane-bound monosomes.

Animals↗