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 793 records · Page 44Linked to original sources
PubMed1985

Correlation of chloroplast and bacterial ribosomal proteins by cross-reactions of antibodies specific to purified Escherichia coli ribosomal proteins.

Immunological homology between chloroplast ribosomal proteins (r-proteins) from a higher plant (Spinacia) and bacterial r-proteins was examined using antibodies prepared against 35 purified Escherichia coli r-proteins. Cross-reactions were determined on cellulose acetate gels and on nitrocellulose paper, after electrophoretic transfer of r-proteins from one- and two dimensional polyacrylamide gels, using peroxidase and fluorescein-conjugated second antibodies for detection (immunoblotting). The specificity of positive cross-reactions was confirmed by absorption experiments using purified E. coli r-proteins. Antisera against five proteins of the small subunit and six proteins of the large subunit of E. coli ribosome (i.e. anti-S7, -S9, -S11, -S12, and -S19; anti-L1, -L2, -L3, -L6, -L13, and -L17) gave cross-reactions. As an inference from this work, and a recent study on the synthesis of certain chloroplast r-proteins in isolated chloroplasts (Eneas-Filho, J., Hartley, M. R., and Mache, R. (1981) Mol. Gen. Genet. 184, 484-488), we suggest that chloroplast r-proteins S7 and L2 are encoded in the organelle DNA.

Antibodies↗
PubMed1988

Wheat germ cytoplasmic ribosomes. Structure of ribosomal subunits and localization of N6,N6-dimethyladenosine by immunoelectron microscopy.

Cytoplasmic ribosomes have been isolated from wheat germ, and the structure of ribosomal subunits has been examined by electron microscopy of negatively stained preparations. Small (40 S) subunits show structural features generally regarded as characteristic of eukaryotic particles, while large (60 S) subunits show shapes that are equally well described by models of prokaryotic 50 S particles. Small subunit 18 S RNA contains 2 residues of N6,N6-dimethyladenosine 19 and 20 residues from the 3'-end (Hagenbüchle, O., Santer, M., Steitz, J. A., and Mans, R. J. (1978) Cell 13, 551-563). Nucleoside analysis by high performance liquid chromatography shows no other residues of this component in the RNA. Anti-dimethyladenosine immunoglobulins were reacted with wheat germ 40 S subunits, and the resulting complexes were studied by electron microscopy in order to localize the nucleoside. In about 90% of the complexes observed, antibody-subunit contact was consistent with a single binding site. We place the dimethyladenosine residues at or near the end of the platform of the 40 S particle in a position nearly equivalent to that previously identified in prokaryotic and chloroplast subunits (Trempe, M. R., and Glitz, D. G. (1981) J. Biol. Chem. 256, 11873-11879).

Adenosine↗
PubMed1986

Use of the cytotoxic nuclease alpha-sarcin to identify the binding site on eukaryotic 5 S ribosomal ribonucleic acid for the ribosomal protein L5.

Treatment of the large subunit of eukaryotic ribosomes with EDTA releases a 7 S ribonucleoprotein complex that contains protein L5 and 5 S rRNA. The region of rat 5 S rRNA that is protected by protein L5 from digestion with the ribonuclease alpha-sarcin includes nucleotides 1-10, 12-22, and 64-116. This domain approximates the combined binding sites for the three proteins (L5, L18, and L25) that associate with Escherichia coli 5 S rRNA. In addition, the region of 5 S rRNA protected by rat ribosomal protein L5 corresponds closely to that occupied by Xenopus transcription factor IIIA.

Animals↗
PubMed1981

Mitochondrial ribosome assembly in Neurospora crassa. Purification of the mitochondrially synthesized ribosomal protein, S-5.

In Neurospora, one mitochondrial ribosomal protein (S-5, Mr = 52,000) is synthesized intramitochondrially and is presumably encoded by mitochondrial DNA. We have developed a rapid method for the purification of S-5 which takes advantage of its high affinity for carboxymethyl-Sepharose in the presence of 6 M urea. Using this method, S-5, at purity greater than 95%, can be prepared by column chromatography in a single batch elution step. The amino acid composition of S-5 was determined. Judged by the contents of hydrophilic and basic amino acids, S-5 is more similar to Escherichia coli and yeast ribosomal proteins than to other mitochondrial translation products which are hydrophobic membrane proteins.

Amino Acids↗
PubMed1982

[Acid proteins of eukaryotic cell ribosomes. Isolation of the protein similar to E. coli L7/L12 from 80S pea ribosomes].

Using ethanol-salt extraction and ion-exchange chromatography, an acid protein was isolated from 80S pea ribosomes. The protein is localized in the large subunit, is phosphorylated and has a molecular weight of 14000 and pI of 4.7. These features and the results of a comparative study of tryptic hydrolysates of the plant protein and of the protein under study suggest that the latter is homologous to the ribosomal protein L7/L12 of a prokaryotic type.

Escherichia coli↗
PubMed1994

Amino acid functional groups involved in the binding of Escherichia coli ribosomal protein S1 to ribosomes and nucleic acids.

Histidine, arginine, tyrosine, lysine and cysteine residues of protein S1 were modified with diethyl pyrocarbonate & rose bengal, 2,3-butanedione (diacetyl), tetranitromethane, pyridoxal 5-phosphate, and N-ethyl-maleimide, respectively. Modification of the residues and the number of modified residues were determined by either fluorescence or UV spectroscopy. The effect of chemical modification on the function of protein S1 was studied with respect to nucleic acid (poly U and M13 ssDNA) binding and ribosome binding properties of the protein. We tested S1 binding to these two types of polynucleotides because of their reported (Draper et al. (1977) PNAS 74, 4786-4790) binding to two different sites on S1. The results indicate that histidine and lysine residues of S1 play an important role in the binding of S1 to both types of nucleic acids and that histidine and to some extent tyrosine residues are involved in the binding of S1 to ribosomes. The Data indicate the need for a re-evaluation of the two nucleic acid binding-site model.

Amino Acids↗
PubMedDate not supplied

[Affinity modification of 40S ribosomal subparticles from human placenta by derivatives of oligoribonucleotides, containing an AUG codon. Ribosomal proteins, forming a codon-anticodon interaction region].

Using 2',3'-O-[4-N-(2-chloroethyl)-N-methylamino]benzylydene derivatives of AUGUn [32P]pC and 4-[N-(2-chloroethyl)-N-methylamino]benzylmethylphosphoamide derivatives of [32P]pAUGUn, the affinity labelling of human placental 40S ribosomal subunits was studied within 40S initiation complexes obtained in the presence of a ternary complex eIF-2.GTP.Met-tRNA(fMet). Analysis of the ribosomal proteins labelled by these mRNA analogues revealed that proteins S3/S3a, S6, S7, and S14/S15 play a key role in the interaction of the template with the 40S subunit in the presence of the ternary complex eIF-2.GTP.Met-tRNA(fMet). Proteins S2, S4, S5, S8, S9, and S17 are also involved in this interaction.

Affinity Labels↗
PubMed1995

Three dimensional model for the 16S ribosomal RNA in the Escherichia coli ribosome.

Molecular modeling has been performed to help correct and refine an approximate three dimensional structure for Eschericia coli 16S rRNA that originated as hand-built wire model. The wire model was built to accommodate the base pairs in 16S rRNA (1), mRNA.16S rRNA interactions (2,3), rRNA.ribosomal protein interactions (see 4), ribosomal protein-ribosomal protein distances (5), intramolecular RNA-RNA UV-crosslinks (6,7) and site-directed mutagenesis experiments (8). In the computer model, individual base-paired regions were constructed separately and then were installed into the expected locations to produce the entire structure. We describe here the considerations, steps and results of this refinement process.

Computer Simulation↗
PubMed1996

[Topography of ribosomal proteins: reconsideration of of protein map of small ribosomal subunit].

Exposure of proteins on the surface of the small (30S) ribosomal subunit of Escherichia coli was studied by the hot tritium bombardment technique. Eight of 21 proteins of the 30 S subunit (S3, S8, S10, S12, S15, S16, S17, and S19) had virtually no groups exposed on the surface of the particle, i.e., they were mainly hidden inside. Seven proteins (S1, S4, S5, S7, S18, S20, and S21) were all well exposed on the surface of the particle, thus being outside proteins. The remaining proteins (S2, S6, S9 and/or S11, S13, and S14) were partially exposed. On the basis of these results a reconcilement of the three-dimensional protein map of the small ribosomal subunit has been done and corrected model is proposed.

Escherichia coli↗
PubMedDate not supplied

Structure and expression of a non-polyadenylated ribosome bound transcript carrying the sequence of human ribosomal protein L7 mRNA in antisense orientation.

Human ribosomal protein L7 has been shown to be involved in the control of translation of distinct mRNAs. In this study we report the existence of an RNA carrying sequences that are complementary (antisense) to the entire coding (sense) region of L7 mRNA. L7 antisense transcripts are not polyadenylated and associate with the large subunit of the ribosome. The antisense sequence is encoded by an intronless gene segment distinct from the active copy of the L7 gene. Upon mitogenic stimulation of lymphocytes and monocytes from mice and humans, complex expression patterns of L7 transcripts are observed.

Animals↗
PubMed1992

Purification and characterization of seven chloroplast ribosomal proteins: evidence that organelle ribosomal protein genes are functional and that NH2-terminal processing occurs via multiple pathways in chloroplasts.

Putative genes for 21 ribosomal proteins (RPs) have been identified in the chloroplast DNA of four plants by nucleotide sequencing and homology comparison but few of the gene products have been characterized. Here we report the purification and N-terminal sequencing of seven proteins from the spinach chloroplast ribosome. The data show them to be the homologues of Escherichia coli RPs L20, L32, L33, L36, S12, S16 and S19, and thus support the view that their genes identified in the chloroplast DNA represent functional genes. The initiating methionine residue was not detected in the mature protein in most cases but it was present in S16, indicating that only the formyl group is removed in this case. This result and the previously reported finding of N-methyl alanine at the N-terminus of chloroplast L2 indicate the existence of multiple N-terminal processing pathways in the chloroplast.

Amino Acid Sequence↗
PubMed1995

The chloroplast gene encoding ribosomal protein S4 in Chlamydomonas reinhardtii spans an inverted repeat--unique sequence junction and can be mutated to suppress a streptomycin dependence mutation in ribosomal protein S12.

The ribosomal protein gene rps4 was cloned and sequenced from the chloroplast genome of Chlamydomonas reinhardtii. The N-terminal 213 amino acid residues of the S4 protein are encoded in the single-copy region (SCR) of the genome, while the C-terminal 44 amino acid residues are encoded in the inverted repeat (IR). The deduced 257 amino acid sequence of C. reinhardtii S4 is considerably longer (by 51-59 residues) than S4 proteins of other photosynthetic species and Escherichia coli, due to the presence of two internal insertions and a C-terminal extension. A short conserved C-terminal motif found in all other S4 proteins examined is missing from the C. reinhardtii protein. In E. coli, mutations in the S4 protein suppress the streptomycin-dependent (sd) phenotype of mutations in the S12 protein. Because we have been unable to identify similar S4 mutations among suppressors of an sd mutation in C. reinhardtii S12 obtained using UV mutagenesis, we made site-directed mutations [Arg68 (CGT) to Leu (CTG and CTT)] in the wild-type rps4 gene equivalent to an E. coli Gln53 to Leu ribosomal ambiguity mutation (ram), which suppresses the sd phenotype and decreases translational accuracy. These mutants were tested for their ability to transform the sd S12 mutation of C. reinhardtii to streptomycin independence. The streptomycin-independent isolates obtained by biolistic transformation all possessed the original sd mutation in rps12, but none had the expected donor Leu68 mutations in rps4. Instead, six of 15 contained a Gln73 (CAA) to Pro (CCA) mutation five amino acids downstream from the predicted mutant codon, irrespective of rps4 donor DNA. Two others contained six- and ten-amino acid, in-frame insertions at S4 positions 90 and 92 that appear to have been induced by the biolistic process itself. Eight streptomycin-independent isolates analyzed had wild-type rps4 genes and may possess mutations identical to previously isolated suppressors of sd that define at least two additional chloroplast loci. Cloned rps4 genes from streptomycin-independent isolates containing the Gln73 to Pro mutation and the 6-amino acid insertion in r-protein S4 transform the sd strain to streptomycin independence.

Amino Acid Sequence↗
PubMed1995

Structure and expression of the gene encoding ribosomal protein S1 from the cyanobacterium Synechococcus sp. strain PCC 6301: striking sequence similarity to the chloroplast ribosomal protein CS1.

We isolated a 38 kDa ssDNA-binding protein from the unicellular cyanobacterium Synechococcus sp. strain PCC 6301 and determined its N-terminal amino acid sequence. A genomic clone encoding the 38 kDa protein was isolated by using a degenerate oligonucleotide probe based on the amino acid sequence. The nucleotide sequence and predicted amino acid sequence revealed that the 38 kDa protein is 306 amino acids long and homologous to the nuclear-encoded 370 amino acid chloroplast ribosomal protein CS1 of spinach (48% identity), therefore identifying it as ribosomal protein (r-protein) S1. Cyanobacterial and chloroplast S1 proteins differ in size from Escherichia coli r-protein S1 (557 amino acids). This provides an additional evidence that cyanobacteria are closely related to chloroplasts. The Synechococcus gene rps1 encoding S1 is located 1.1 kb downstream from psbB, which encodes the photosystem II P680 chlorophyll a apoprotein. An open reading frame encoding a potential protein of 168 amino acids is present between psbB and rps1 and its deduced amino acid sequence is similar to that of E. coli hypothetical 17.2 kDa protein. Northern blot analysis showed that rps1 is transcribed as a monocistronic mRNA.

Amino Acid Sequence↗
PubMed1978

Chromosome location of the ribosomal genes in Triturus vulgaris meridionalis (Amphibia Urodela). III. Inheritance of the chromosomal sites for 18S + 28S ribosomal RNA.

In Triturus vulgaris meridionalis, the 18S + 28S rDNA sequences have been shown to be located in a number of additional chromosomal sites besides the nucleolus organizing region. The additional ribosomal sites have been found to vary as to their number and chromosomal location in different individuals of the species.--The data presented in this study concern the chromosomal distribution of the ribosomal sequences as analyzed by in situ hybridization technique in two individuals as well as in their offspring. The evidence obtained by this analysis indicates quite clearly that all 18S + 28S rRNA sites present in each individual genome are inherited according to simple mendelian principles.

Animals↗
PubMed1983

Mapping of the genes for Bacillus subtilis ribosomal proteins S6 and S16: comparison of the chromosomal distribution of ribosomal protein genes in this bacterium with the distribution in Escherichia coli.

Using mutants of Bacillus subtilis with alterations in the small subunit ribosomal proteins S6 and S16, the corresponding genes were mapped. rpsF was located between purA and cysA, close to the origin of replication. rpsP was located near pyrD, at about 135 degrees on the linkage map. The distribution on the chromosome of the ribosomal protein gene loci so far identified in B. subtilis was compared with the distribution of the genes for the same proteins in Escherichia coli. Considered in terms of relative distance from the origin and terminus of chromosomal replication, the order was the same in both species with the sole exception of protein S6.

Bacillus subtilis↗
PubMed1982

Analysis of revertants of a ribosomal mutation in Podospora anserina: evidence for new ribosomal mutations which confer hypersensitivity to paromomycin.

This paper describes the analysis of cold-resistant revertants of a cold-sensitive mutant. Pm1-1 is a ribosomal mutation screened for its paromomycin resistance. Suppression of its cold sensitivity occurs with two kinds of external mutations localized in two different loci. One of them, PmB, is assumed to be a ribosomal gene. PmB mutations confer hypersensitivity to paromomycin in vivo as well as in vitro in a cell-free protein synthesis system.

Ascomycota↗
PubMed1995

Amino acid sequence of the ribosomal protein HS23 from the halophilic Haloarcula marismortui and homology studies to other ribosomal proteins.

The ribosomal protein HS23 from the 30S subunit of the extreme halophilic Haloarcula marismortui, belonging to the group of archaea, was isolated either by RP-HLPLC or two-dimensional polyacrylamide gel electrophoresis. The complete amino acid sequence was determined by automated N-terminal microsequencing. The protein consists of 123 residues with a corresponding molecular mass of 12,552 Da as determined by electrospray mass spectroscopy; the pI is 11.04. Homology studies reveal similarities to the eukaryotic ribosomal protein S8 from Homo sapiens, Rattus norvegicus, Leishmania major, and Saccharomyces cerevisiae.

Amino Acid Sequence↗