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PubMed1985

Evidence for the exchangeability of acidic ribosomal proteins on cytoplasmic ribosomes in regenerating rat liver.

We purified acidic ribosomal proteins (P1 and P2) in good yield from rat liver ribosomes by precipitation of ribosomes with MgCl2 prior to ethanol extraction and chromatography of the extract on a column of CM-cellulose at pH 4.8. The newly-synthesized acidic ribosomal proteins in regenerating rat liver, labeled in vivo with [3H]leucine, were rapidly incorporated into cytoplasmic ribosomes without any detectable time lag and, after reaching a maximum at 30 min, they gradually disappeared from the ribosomes, suggesting a short metabolic-life. However, it was found later that they were re-incorporated slowly when newly-labeled proteins were "chased" by an injection of a large amount of cold leucine intraperitoneally at 15 min after the injection of [3H]leucine. Furthermore, in a long-term experiment, acidic ribosomal proteins were found to disappear with a half-life of 100 h from the ribosomes. Thus, these results suggest that acidic ribosomal proteins have a long metabolic life and are exchangeable on cytoplasmic ribosomes in regenerating rat liver.

Animals↗
PubMed1986

Effect of heat shock on ribosome structure: appearance of a new ribosome-associated protein.

After a nonlethal but heat shock protein-inducing hyperthermic treatment, ribosomes isolated from Tetrahymena thermophila contained an additional 22-kilodalton protein (p22). When maximally ribosome associated, this protein was found to be on the small subunit in a 1:1 stoichiometric ratio with other ribosomal proteins. Using an antiserum directed against the purified 22-kilodalton protein, we found that non-heat-shocked and heat-shocked cells contain identical amounts of this protein, the only difference being that in the stressed cells p22 is entirely ribosome bound, whereas in the unstressed cells p22 has little or no detectable ribosome association. Because the two-dimensional electrophoretic properties of p22 showed no alterations after heat shock, this change in state of ribosome-p22 interaction does not appear to be caused by a chemical modification of p22. When not strongly ribosome associated, p22 is not found free in the cytoplasm. During that time in heat shock when p22 is first becoming ribosome associated, it is found preferentially on polysomal ribosomes. Subsequently, all ribosomes, whether polysome bound or not, obtain a bound p22. The functional significance of this association is discussed.

Electrophoresis, Polyacrylamide Gel↗
PubMed1986

[Study of the surface of Escherichia coli ribosomes and ribosomal particles by the tritium bombardment method].

A new technique of atomic tritium bombardment has been used to study the surface topography of Escherichia coli ribosomes and ribosomal subunits. The technique provides for the labeling of proteins exposed on the surface of ribosomal particles, the extent of protein labeling being proportional to the degree of exposure. The following proteins were considerably tritiated in the 70S ribosomes: S1, S4, S7, S9 and/or S11, S12 and/or L20, S13, S18, S20, S21, L1, L5, L6, L7/L12, L10, L11, L16, L17, L24, L26 and L27. A conclusion is drawn that these proteins are exposed on the ribosome surface to an essentially greater extent than the others. Dissociation of 70S ribosomes into the ribosomal subunits by decreasing Mg2+ concentration does not lead to the exposure of additional ribosomal proteins. This implies that there are no proteins on the contacting surfaces of the subunits. However, if a mixture of subunits has been subjected to centrifugation in a low Mg2+ concentration at high concentrations of a monovalent cation, proteins S3, S5, S7, S14, S18 and L16 are more exposed on the surface of the isolated 30S and 50S subunits than in the subunit mixture or in the 70S ribosomes. The exposure of additional proteins is explained by distortion of the native quaternary structure of ribosomal subunits as a result of the separation procedure. Reassociation of isolated subunits at high Mg2+ concentration results in shielding of proteins S3, S5, S7 and S18 and can be explained by reconstitution of the intact 30S subunit structure.

Escherichia coli↗
PubMed1994

Recognition of novel and divergent higher plant chloroplast ribosomal proteins by Escherichia coli ribosome during in vivo assembly.

Architecture of higher plant chloroplast ribosomes involves additional protein domains over that found in the Escherichia coli ribosome, although the rRNAs in these two kinds of ribosomes are very similar in length and sequence (Subramanian, A. R. (1993) Trends Biochem. Sci. 18, 177-180). Here, we show that two chloroplast-specific protein domains (a novel chloroplast ribosomal protein of the 30 S subunit, called Psrp-1 or S22, and a divergent protein of the 50 S subunit with long terminal extensions and low homology to its E. coli counterpart, L21) are both incorporated in E. coli ribosomes and polysomes when their gene constructs are expressed in E. coli. Also, the 67-residue NH2-terminal extension in chloroplast L21 by itself is incorporated. Thus, our results indicate preexisting binding sites for novel chloroplast-specific ribosomal proteins/domains on eubacterial ribosomes. Additionally, we observed cleavage of the chloroplast-targeting transit peptide (present in the expressed Psrp-1 precursor), indicating protease(s) of the required specificity in E. coli cells. The expression of chloroplast L21 with its NH2-terminal extension was inhibitory to E. coli growth, suggesting a drastic effect of the latter on some property of L21. Expression of Psrp-1 was neutral, consistent with a function only in chloroplast translation. Based on analysis of the assembly of Psrp-1 and various L21 fragments in E. coli ribosomes, a general model for studying ribosomal protein-ribosome interactions is suggested.

Base Sequence↗
PubMed1996

Depurination of A4256 in 28 S rRNA by the ribosome-inactivating proteins from barley and ricin results in different ribosome conformations.

Ribosomal function in protein synthesis requires dynamic flexibility of the ribosomal structure. The two translational inhibitors derived from seeds of ricin and barley destroy the dynamic properties of the ribosome by selective depurination of A4256 in the phylogenetically conserved alpha-sarcin/ricin loop of mouse 28 S rRNA. As the alpha-sarcin/ricin loop is involved in binding of elongation factors to the ribosome, depurination blocks the protein synthesis elongation cycle. Depurination by the barley translational inhibitor (BTI) mainly effects eEF-1 alpha related functions, while ricin interferes with the interaction of eEF-2 with the ribosome. Analysis of the ribosomal structure after inhibitor shows that the accessibility of the rRNAs for single-strand-specific chemical modification was altered. Reactivity changes were seen in domains I, II and V of 28 S rRNA and in 5 S rRNA. A majority of the reactivity changes were found in putative functional regions of the rRNAs, such as the regions involved in peptidyltransferase activity, subunit interaction and in the binding of elongation factors. Most of the observed structural changes made the rRNAs less accessible for chemical modification, suggesting that the ribosomal particles became less flexible after inhibitor treatment. Moreover, the modification patterns obtained from the two inhibitor-treated ribosomal particles were only partly overlapping, indicating that the structure of the large ribosomal subunit differed after ricin and BTI treatment. Surprisingly, depurination in the alpha-sarcin/ricin loop of 28 S rRNA also affected the structure of the 3' major domain in 18 S rRNA.

Adenine↗
PubMed1969

The effect of pancreatic ribonuclease on rabbit reticulocyte ribosomes and its interpretation in terms of ribosome structure.

1. Parts of the 16s and 30s RNA species of reticulocytes are readily hydrolysed by pancreatic ribonuclease. The biological activity of the ribosomes is diminished after treatment with low concentrations of the enzyme (e.g. 1ng. of ribonuclease/2.5mg. of polyribosome fraction/ml.). A high proportion of the chain scissions are ;hidden' owing to the secondary structure of the RNA moiety. 2. As the concentration of ribonuclease is increased RNA is lost from the ribosome. About 20-30% of the RNA may be removed from the ribosome without altering appreciably its sedimentation coefficient or its appearance in the electron microscope. 3. The amount of RNA removed from the ribosome is not increased by raising the concentration of enzyme from about 1mug. to 2.5mg. of ribonuclease/2.5mg. of polyribosome fraction/ml., or by increasing the temperature from 0 degrees to 30 degrees , or by first converting the RNA moiety into a single-stranded form before exposure to ribonuclease. 4. Untreated polyribosomes aggregate at about 75 degrees , whereas ribosomes treated with ribonuclease aggregate at about 45 degrees . The aggregates that are found on heating ribosomes after enzymic hydrolysis contain about 40-50% of the complement of RNA of intact ribosomes. 5. From the size of the fragments of RNA isolated from RNA-depleted ribosomes it is inferred that there is one site/60-100 nucleotides that is sensitive to ribonuclease. 6. The RNA moiety of RNA-depleted ribosomes has some double-helical character as shown by the optical properties and X-ray-diffraction pattern of ribonuclease-treated ribosomes and by the ;melting' properties of the isolated RNA. 7. Subparticles prepared by titration with an excess of EDTA are readily hydrolysed by ribonuclease to fragments of S(20,w) less than 4s, in contrast with the intact particle.

Animals↗
PubMed2001

The small subunit of the mammalian mitochondrial ribosome. Identification of the full complement of ribosomal proteins present.

Identification of all the protein components of the small subunit (28 S) of the mammalian mitochondrial ribosome has been achieved by carrying out proteolytic digestions of whole 28 S subunits followed by analysis of the resultant peptides by liquid chromatography and tandem mass spectrometry (LC/MS/MS). Peptide sequence information was used to search the human EST data bases and complete coding sequences of the proteins were assembled. The human mitochondrial ribosome has 29 distinct proteins in the small subunit. Fourteen of this group of proteins are homologs of the Escherichia coli 30 S ribosomal proteins S2, S5, S6, S7, S9, S10, S11, S12, S14, S15, S16, S17, S18, and S21. All of these proteins have homologs in Drosophila melanogaster, Caenorhabditis elegans, and Saccharomyces cerevisiae mitochondrial ribosomes. Surprisingly, three variants of ribosomal protein S18 are found in the mammalian and D. melanogaster mitochondrial ribosomes while C. elegans has two S18 homologs. The S18 homologs tend to be more closely related to chloroplast S18s than to prokaryotic S18s. No mitochondrial homologs to prokaryotic ribosomal proteins S1, S3, S4, S8, S13, S19, and S20 could be found in the peptides obtained from the whole 28 S subunit digests or by analysis of the available data bases. The remaining 15 proteins present in mammalian mitochondrial 28 S subunits (MRP-S22 through MRP-S36) are specific to mitochondrial ribosomes. Proteins in this group have no apparent homologs in bacterial, chloroplast, archaebacterial, or cytosolic ribosomes. All but two of these proteins have a clear homolog in D. melanogaster while all but three can be found in the genome of C. elegans. Five of the mitochondrial specific ribosomal proteins have homologs in S. cerevisiae.

Amino Acid Sequence↗
PubMed1984

Immunological similarities between specific chloroplast ribosomal proteins from Chlamydomonas reinhardtii and ribosomal proteins from Escherichia coli.

Polyclonal antibodies were elicited against seven of the 33 different proteins of the large subunit of the chloroplast ribosome from Chlamydomonas reinhardtii. Three of these proteins are synthesized in the chloroplast and four are made in the cytoplasm and imported. In western blots, six of the seven antisera are monospecific for their respective large subunit ribosomal proteins, and none of these antisera cross-reacted with any chloroplast small subunit proteins from C. reinhardtii. Antisera to the three chloroplast-synthesized ribosomal proteins cross-reacted with specific Escherichia coli large subunit proteins of comparable charge and molecular weight. Only one of the four antisera to the chloroplast ribosomal proteins synthesized in the cytoplasm cross-reacted with an E. coli large subunit protein. None of the antisera cross-reacted with any E. coli small subunit proteins. On the assumption of a procaryotic, endosymbiotic origin for the chloroplast, those chloroplast ribosomal proteins still synthesized within the organelle appear to have retained more antigenic sites in common with E. coli ribosomal proteins than have those which are now the products of cytoplasmic protein synthesis. Antisera to this cytoplasmically synthesized group of chloroplast ribosomal proteins did not recognize any antigenic sites among C. reinhardtii cytoplasmic ribosomal proteins, suggesting that the genes for the cytoplasmically synthesized chloroplast ribosomal proteins either are not derived from the cytoplasmic ribosomal protein genes or have evolved to a point where no antigenic similarities remain.

Biological Evolution↗
PubMed1974

Chloroplast and cytoplasmic ribosomes of Euglena: selective binding of dihydrostreptomycin to chloroplast ribosomes.

Dihydrostreptomycin binds preferentially to chloroplast ribosomes of wild-type Euglena gracilis Klebs var. bacillaris Pringsheim. The K(diss) for the wild-type chloroplast ribosome-dihydrostreptomycin complex is 2 x 10(-7) M, a value comparable with that found for the Escherichia coli ribosome-dihydrostreptomycin complex. Chloroplast ribosomes isolated from the streptomycin-resistant mutant Sm(1) (r)BNgL and cytoplasmic ribosomes from wild-type have a much lower affinity for the antibiotic. The K(diss) for the chloroplast ribosome-dihydrostreptomycin complex of Sm(1) (r) is 387 x 10(-7) M, and the value for the cytoplasmic ribosome-dihydrostreptomycin complex of the wild type is 1,400 x 10(-7) M. Streptomycin competes with dihydrostreptomycin for the chloroplast ribosome binding site, and preincubation of streptomycin with hydroxylamine prevents the binding of streptomycin to the chloroplast ribosome. These results indicate that the inhibition of chloroplast development and replication in Euglena by streptomycin and dihydrostreptomycin is related to the specific inhibition of protein synthesis on the chloroplast ribosomes of Euglena.

Binding Sites↗
PubMed1985

Induction of the chloramphenicol acetyltransferase gene cat-86 through the action of the ribosomal antibiotic amicetin: involvement of a Bacillus subtilis ribosomal component in cat induction.

The plasmid gene cat-86 and the cat gene resident on pC194 each encode chloramphenicol-inducible chloramphenicol acetyltransferase activity in Bacillus subtilis. Chloramphenicol induction has been proposed to result from chloramphenicol binding to ribosomes, which then permits the drug-modified ribosomes to perform events essential to induction. If this proposal were correct, B. subtilis mutants containing chloramphenicol-insensitive ribosomes should not permit chloramphenicol induction of either cat-86 or pC194 cat. However, we and others have been unable to isolate chloramphenicol-resistant ribosomal mutants of B. subtilis 168. We therefore developed a simple procedure for screening other antibiotics for the potential to induce cat-86 expression. One antibiotic, amicetin, was found to be an effective inducer of cat-86 but not of the cat gene on pC194. Amicetin and chloramphenicol each interact with the 50S ribosomal subunit, and the mechanism of cat-86 induction by both drugs may be similar. Amicetin-resistant mutants of B. subtilis were readily isolated, and in none of six mutants tested was cat-86 detectably inducible by amicetin, although the chloramphenicol-inducible phenotype was retained. The ami-1 mutation which is present in one of these amicetin-resistant mutants was mapped by PBS1 transduction to the "ribosomal gene cluster" adjacent to cysA. Additionally, ribosomes from cells harboring the ami-1 mutation contained an altered BL12a protein, as detected in two-dimensional polyacrylamide gel electrophoresis. Lastly, an in vitro protein-synthesizing system that uses ribosomes from an ami-1-containing cell line was more resistant to amicetin than a system that uses ribosomes from an amicetin-sensitive but otherwise isogenic strain. These results indicate that the host mutation, ami-1, which effectively abolished the inducibility of cat-86 by amicetin, altered a ribosomal component.

Acetyltransferases↗
PubMed1967

Ribosomes and ribosomal protein from Neurospora crassa. I. Physical, chemical, and immunochemical properties.

Ribosomes from Neurospora crassa, initially characterized by ultracentrifugal and immunochemical analyses, have been used to prepare ribosomal protein for physical, chemical, and immunochemical study. The acrylamide gel disc electrophoretic profiles of Neurospora ribosomal protein exhibit a degree of heterogeneity comparable to what has been observed in other systems. Only by chemical modification or by aggregation of the protein do alterations in the profile become apparent. Disulfide-bond formation appears to play a role in the aggregation of ribosomal protein to complexes of S(20,w) = 200. The aggregation can be prevented by alkylation of -SH groups, and protein treated in this fashion has a subunit molecular weight of about 20,000 as determined by equilibrium centrifugation. Finger-printing of tryptic peptides indicates that more than one unique sequence of amino acids must be present in ribosomal protein, although gross primary structural heterogeneity is questioned. Antigenic heterogeneity is much less apparent; only a few precipitin bands are resolved by immunodiffusion tests, although complete reactivity of total ribosomal protein is suggested by quantitative precipitin analysis. The antigenically active ribosomal protein components appear to reside in at least two fractions; one is removed readily from the ribosome by CsC1 treatment. Ribosomal protein of N. crassa possesses antigenic determinants present in E. coli ribosomal protein as judged by spur formation in immunodiffusion tests.

Amino Acids↗
PubMed1996

The accessibility of yeast ribosomal protein L1 as probed by proteolysis and site-directed mutagenesis is different in intact 60 and 80 S ribosome.

Accessible regions of protein L1 in intact 60 and 80 S ribosomes from Saccharomyces cerevisiae were first detected by controlled proteolysis. The N-terminal region of L1 in either 60 S or 80 S particles, was inaccessible to proteases, but the central and C-terminal regions were accessible. The accessibility of the central region differed depending on the ribosome state. These regions were further examined by determination of the chemical reactivity of specific cysteine residues introduced into these regions by site-directed mutagenesis. All cysteine mutant proteins were capable of binding yeast 5 S rRNA in vitro and the ribosomes containing the mutant proteins were functional in vivo. Residues Cys-257 and Cys-275 were modified in both the 60 and 80 S ribosomes but the modification rates were different in the two ribosome states. Both residues Cys-62 and Cys-286 were inaccessible in 80 S or 60 S ribosomes. Taken together, the present study identified several accessible regions of L1 in intact ribosomes and further showed that the accessibility of some of the regions was altered upon ribosomal subunit association. The most likely interpretation of these results is that the conformation of the ribosomal protein L1 was altered upon ribosomal subunit association.

Amino Acid Sequence↗
PubMed1984

Ribosomal proteins: their structure and spatial arrangement in prokaryotic ribosomes.

During the last 15 years of ribosomal protein study, enormous progress has been made. Each of the proteins from E. coli ribosomes has been isolated, sequenced, and immunologically and physically characterized. Ribosomal proteins from other sources (e.g., from some bacteria, yeast, and rat) have been isolated and studied as well. Several proteins have recently been crystallized, and from the X-ray studies it is expected that much important information on the three-dimensional structure will be forthcoming. Many other proteins can probably be crystallized if suitable preparative procedures and crystallization conditions are found. Tremendous progress has also been made in deciphering the architecture of the ribosome. A battery of different methods has been used to provide the nearest neighbor distances of the ribosomal proteins in situ. Definitive measurements are now emanating from neutron-scattering experiments which also promise to give reasonably accurate radii of gyration of the proteins in situ. In turn, refined immune electron microscopy results supplement the neutron-scattering data and also position the proteins on the subunits themselves. This cannot be done by the other methods. Determination of the three-dimensional RNA structure within the ribosome is still in its infancy. Nonetheless, it is expected that by combining the data from protein-RNA and from RNA-RNA cross-linking studies, the structure of the RNA in situ can be unraveled. Of great interest is the fact that ribosomal subunits and ribosomes themselves have now been crystallized, and low-resolution structural maps have already been obtained. However, to grow suitable crystals and to resolve the ribosomal structure at a sufficiently high resolution remains a great challenge and task to biochemists and crystallographers.

Amino Acid Sequence↗
PubMed2004

Visualization of ribosome-recycling factor on the Escherichia coli 70S ribosome: functional implications.

After the termination step of protein synthesis, a deacylated tRNA and mRNA remain associated with the ribosome. The ribosome-recycling factor (RRF), together with elongation factor G (EF-G), disassembles this posttermination complex into mRNA, tRNA, and the ribosome. We have obtained a three-dimensional cryo-electron microscopic map of a complex of the Escherichia coli 70S ribosome and RRF. We find that RRF interacts mainly with the segments of the large ribosomal subunit's (50S) rRNA helices that are involved in the formation of two central intersubunit bridges, B2a and B3. The binding of RRF induces considerable conformational changes in some of the functional domains of the ribosome. As compared to its binding position derived previously by hydroxyl radical probing study, we find that RRF binds further inside the intersubunit space of the ribosome such that the tip of its domain I is shifted (by approximately 13 A) toward protein L5 within the central protuberance of the 50S subunit, and domain II is oriented more toward the small ribosomal subunit (30S). Overlapping binding sites of RRF, EF-G, and the P-site tRNA suggest that the binding of EF-G would trigger the removal of deacylated tRNA from the P site by moving RRF toward the ribosomal E site, and subsequent removal of mRNA may be induced by a shift in the position of 16S rRNA helix 44, which harbors part of the mRNA.

Cryoelectron Microscopy↗
PubMed2006

Eukaryotic ribosomal proteins lacking a eubacterial counterpart: important players in ribosomal function.

The ribosome is a macromolecular machine responsible for protein synthesis in all organisms. Despite the enormous progress in studies on the structure and function of prokaryotic ribosomes, the respective molecular details of the mechanism by which the eukaryotic ribosome and associated factors construct a polypeptide accurately and rapidly still remain largely unexplored. Eukaryotic ribosomes possess more RNA and a higher number of proteins than eubacterial ribosomes. As the tertiary structure and basic function of the ribosomes are conserved, what is the contribution of these additional elements? Elucidation of the role of these components should provide clues to the mechanisms of translation in eukaryotes and help unravel the molecular mechanisms underlying the differences between eukaryotic and eubacterial ribosomes. This article focuses on a class of eukaryotic ribosomal proteins that do not have a eubacterial homologue. These proteins play substantial roles in ribosomal structure and function, and in mRNA binding and nascent peptide folding. The role of these proteins in human diseases and viral expression, as well as their potential use as targets for antiviral agents is discussed.

Animals↗
PubMed1981

Cold-sensitive ribosome assembly in an Escherichia coli mutant lacking a single methyl group in ribosomal protein L3.

Ribosomal protein methylation has been well documented but its function remains unclear. We have examined this phenomenon using an Escherichia coli mutant (prmB2), which fails to methylate glutamine residue number 150 of ribosomal protein L3. This mutant exhibits a cold-sensitive phenotype: its growth rate at 22 degrees C is abnormally low in complete medium. In addition, strains with this mutation accumulate abnormal and unstable ribosomal particles; 50-S and 30-S subunits are formed, but at a lower rate. Once assembled, ribosomes with unmethylated L3 are fully active by several criteria. (a) Protein synthesis in vitro with purified 70-S prmB2 ribosomes is as active as wild-type using either a natural (R17) or an artificial [poly(U)] messenger. (b) The induction of beta-galactosidase in vivo exhibits normal kinetics and the enzyme has a normal rate of thermal denaturation. (c) These ribosomes are standard when exposed in vitro to a low magnesium concentration or increasing molarities of LiCl. Efficient methylation of L3 in vitro requires either unfolded ribosomes or a mixture of ribosomal protein and RNA. We suggest that the L3-specific methyltransferase may qualify as one of the postulated 'assembly factors' of the E. coli ribosome.

Cold Temperature↗
PubMed1993

Yeast ribosomal protein L1 is required for the stability of newly synthesized 5S rRNA and the assembly of 60S ribosomal subunits.

Ribosomal protein L1 from Saccharomyces cerevisiae binds 5S rRNA and can be released from intact 60S ribosomal subunits as an L1-5S ribonucleoprotein (RNP) particle. To understand the nature of the interaction between L1 and 5S rRNA and to assess the role of L1 in ribosome assembly and function, we cloned the RPL1 gene encoding L1. We have shown that RPL1 is an essential single-copy gene. A conditional null mutant in which the only copy of RPL1 is under control of the repressible GAL1 promoter was constructed. Depletion of L1 causes instability of newly synthesized 5S rRNA in vivo. Cells depleted of L1 no longer assemble 60S ribosomal subunits, indicating that L1 is required for assembly of stable 60S ribosomal subunits but not 40S ribosomal subunits. An L1-5S RNP particle not associated with ribosomal particles was detected by coimmunoprecipitation of L1 and 5S rRNA. This pool of L1-5S RNP remained stable even upon cessation of 60S ribosomal subunit assembly by depletion of another ribosomal protein, L16. Preliminary results suggest that transcription of RPL1 is not autogenously regulated by L1.

Alleles↗
PubMed1995

Ribosome modulation factor: stationary growth phase-specific inhibitor of ribosome functions from Escherichia coli.

Ribosome modulation factor (RMF) is an Escherichia coli protein associated with 100S ribosome dimers, which are formed at stationary growth phase or in slowly growing cells. RMF either purified from stationary-phase ribosomes or synthesized by a chemical method was examined for its functions. By adding either natural or synthetic RMF to 70S ribosomes prepared from both exponentially growing and stationary phase cells, 100S ribosome dimers were generated in a concentration-dependent manner. Protein synthesis in vitro was inhibited concomittantly with the formation of 100S ribosomes. The binding of aminoacyl-tRNA to ribosomes was inhibited in parallel. Taken together we propose that RMF is a stationary phase-specific inhibitor of ribosome functions and 100S dimers are stored forms of ribosomes.

Amino Acid Sequence↗