TY - JOUR. T1 - C-MYC Messenger-RNA in Cytoskeletal-Bound Polysomes in Fibroblasts. AU - HESKETH, J E AU - Campbell, Gillian Patricia. AU - WHITELAW, P F PY - 1991/3/1. Y1 - 1991/3/1. N2 - 3T3 fibroblasts were treated sequentially with 25 mM-KCl/0.05% Nonidet P40, mM-KCl/0.05% Nonidet P40 and finally with 1% Nonidet P40/1% deoxycholate in orde to release free, cytoskeletal-bound and membrane-bound polysomes respectively. The membrane-bound fraction was enriched in the mRNA for the membrane protein beta-2-microglobulin, whereas the cytoskeletal-bound polysomes were enriched in c-myc mRNA. Actin mRNA was present in both free and cytoskeletal-bound polysomes. The results suggest that cytoskeletal-bound polysomes are involved in the translation of specific mRNA species.. AB - 3T3 fibroblasts were treated sequentially with 25 mM-KCl/0.05% Nonidet P40, mM-KCl/0.05% Nonidet P40 and finally with 1% Nonidet P40/1% deoxycholate in orde to release free, cytoskeletal-bound and membrane-bound polysomes ...
Abstract: Among various membrane-bound polyribosomes from chicken embryos the polyribosomes loosely bound with membranes proved to be highly active in synthesis of total proteins as well as of collagens in vitro. These data suggest that polyribosomes loosely bound with membranes were not an impurity of free polyribosomes in the total preparation of the membrane-bound polyribosomes. These polyribosomes constituted a definite class of polyribosomes active in the synthesis of secreted proteins (i.e. of collagen). In polyribosome fractions identified by their size (monosomes, light and heavy polyribosomes) all the three fractions of loosely-bound polyribosomes as well as light and heavy fractions of tightly-bound polyribosomes were active in synthesis of total proteins. Differences between tightly-and loosely-bound polyribosomes were noted also in studies of cell-free synthesis of collagen proteins. Heavy fractions of tightly-bound polyribosomes were the most active in synthesis of these proteins, ...
Plant growth throughout the world is often limited by unfavourable environmental conditions. This paper reports results of a study on long- and short-term osmotic stress (−0.5 MPa) followed by a recovery on in vitro translational capacity of polysomes and on the composition of polysome-associated proteins in germinating pea (Pisum sativum L.) seeds. Here we show that, under osmotic stress, cytoskeleton-bound polysomes were charaterized by the highest translation activity, which may be indicative of an important role that this population of polysomes plays in the synthesis of the so-called "stress proteins". We also find out that in response to osmotic stress, new proteins (22.01, 96.47 and 105.3 kDa), absent in the unstressed sample, associated with the total pool of polysomes, whereas the protein of 22.95 kDa, which was present in the embryonic tissue of seeds germinating under unstressed conditions, disappeared. These changes may have affected both the stability and the translational ...
RNA molecules from nuclear and cytoplasmic polyribosomes of adenovirus-infected HeLa cells were compared by hybridization to analyse the sequence content. Nuclear polyribosomes were released by exposure of intact detergent-washed nuclei to poly(U) and purified. Cytoplasmic polyribosomes were also purified from the same cells. To show that nuclear polyribosomes contain ribosomes linked by mRNA, polyribosomes were labelled with methionine and uridine in the presence of actinomycin D in adenovirus-infected cells. Purified nuclear polyribosomes were treated with EDTA under conditions which dissociate polyribosomes into ribosomes and subunits with a simultaneous release of mRNA, and sedimented. The treatment dissociated these polyribosomes, releasing the mRNA from them. Radiolabelled total RNA from each polyribosome population was fractionated in sucrose gradients into several pools or hybridized to intact adenovirus DNA to select virus-specific RNA. Sucrose-gradient-fractionated pool-3 RNA (about ...
Polyribosome aggregation state in growing tissues of barley and wheat leaf of stems of pea and squash was studied in relation to seedling growth and water status of the growing tissue in plants at various levels of osmotic stress. It was found to be highly correlated with water potential and osmotic potential of the growing tissue and with leaf of stem elongation rate. Stress rapidly reduced polyribosome content and water status in growing tissues of barley leaves; changes were slow and slight in the non-growing leaf blade. Membrane-bound and free polyribosomes were equally sensitive to stress-induced disaggregation. Incorporation of /sup 32/PO/sub 4//sup 3 -/ into ribosomal RNA was rapidly inhibited by stress, but stability of poly(A)/sup +/RNA relative to ribosomal RNA was similar in stressed and unstressed tissues, with a half-life of about 12 hours. Stress also caused progressive loss of poly(A)/sup +/RNA from these tissues. Quantitation of poly(A) and in vitro messenger template activity in ...
TY - JOUR. T1 - Component of splicing factor SF3b plays a key role in translational control of polyribosomes on the endoplasmic reticulum. AU - Ueno, Tomonori. AU - Taga, Yuki. AU - Yoshimoto, Rei. AU - Mayeda, Akila. AU - Hattori, Shunji. AU - Ogawa-Goto, Kiyoko. PY - 2019/5/7. Y1 - 2019/5/7. N2 - One of the morphological hallmarks of terminally differentiated secretory cells is highly proliferated membrane of the rough endoplasmic reticulum (ER), but the molecular basis for the high rate of protein biosynthesis in these cells remains poorly documented. An important aspect of ER translational control is the molecular mechanism that supports efficient use of targeted mRNAs in polyribosomes. Here, we identify an enhancement system for ER translation promoted by p180, an integral ER membrane protein we previously reported as an essential factor for the assembly of ER polyribosomes. We provide evidence that association of target mRNAs with p180 is critical for efficient translation, and that SF3b4, ...
The plant endomembrane system plays vital roles for synthesis, modification and secretion of proteins and lipids. From the classic view, only mRNAs encoding secreted proteins could be targeted to the endoplasmic reticulum (ER) for translation via a co-translational translocation manner, however, recently this model has been challenged by accumulative evidence that lots of cytosolic mRNAs could also associate with ER, and that some categories of small RNAs are enriched on ER. These results suggested unrevealed functions of ER beyond our current knowledge. The large scale identification of RNAs and proteins on microsome is crucial to demonstrating the ER function and the studies will be boosted by next generation sequencing technology. This protocol provides a technical workflow to isolate the cytosol, microsome, free polysome (FP) and membrane bound polysome (MBP) from plant tissue. The isolated fractions are suitable for genome wide profiling of mRNAs, small RNAs and proteins.
Polyribosomes containing nascent [3H]proline-labeled collagen chains were isolated from chick embryo fibroblasts in culture. These nascent chains were nearly completely hydroxylated, as indicated by the presence of [3H]hydroxyproline and high hydroxyproline/proline ratios. The polyribosomes were suspended in D2O at 15 degrees and the infrared spectrum was determined using a reference cell containing collagen-depleted polyribosomes in D2O, matched to equal RNA content. The amide I and amide II bands were observed. When the polyribosomes were heated in D2O at 44 degrees in the infrared cells, the N--D amide II absorbance at 1480 cm-1 increased markedly, indicating that H leads to D exchange had occurred. Collagen-depleted polyribosomes showed no such changes in absorbance at 1450-1480 cm-1 upon heating. Polyribosomes recovered from the infrared cells after treatment at 44 degrees and cooling still contained collagen, as indicated by their [3H]hydroxyproline content. These data indicate that ...
Define polyribosome: a cluster of ribosomes linked together by a molecule of messenger RNA and forming the site of protein synthesis
Previous studies have demonstrated that polyribosomes are selectively positioned beneath postsynaptic sites on CNS neurons. In spine-bearing neurons, these polyribosomes are selectively localized at the base of the spines, and occasionally within spine heads. The present study evaluates whether there are relationships between the polyribosomes and other organelles of the postsynaptic cytoplasm, including membranous cisterns and spine apparatuses. Dendritic spines from the dentate gyrus and hippocampus of the rat were analyzed at the electron-microscopic level in 2 ways. First, relatively thick sections were prepared for electron microscopy, and spines were photographed in stereo using a goniometer stage. Second, conventional serial thin sections were taken, and spines were reconstructed. From the stereo photographs and serial reconstructions, we determined the proportion of polyribosomes that was associated with membranous cisterns. We also counted the number of ribosomes per cluster to ...
Looking for polysome? Find out information about polysome. A complex of ribosomes bound together by a single messenger ribonucleic acid molecule. Also known as polyribosome Explanation of polysome
48. Zavolan, M., Gerber, A.P. (2018) Mirroring the multifaceted role of RNA and its partners in gene expression. FEBS Lett. 592(17):2825-2827. doi: 10.1002/1873-3468.13230. 47. Albihlal, W.A., Gerber, A.P. (2018) Unconventional RNA-binding proteins: an uncharted zone in RNA biology. FEBS Lett. 592(17), 2917-2931. doi: 10.1002/1873-3468.13161. 46. Iadevaia, V. Matia-González, A.M, Gerber, A.P. (2018) An oligonucleotide-based tandem RNA isolation procedure to recover eukaryotic mRNA-protein complexes. J. Vis. Exp. 138. doi: 10.3791/58223. 45. King, H.A., El-Sharif, H.F., Matia-González, A.M., Iadevaia, V., Fowotade, A., Reddy, S.M., Gerber, A.P. (2017) Generation of ribosome imprinted polymers for sensitive detection of translational responses. Sci. Rep. 7(1), 6542. doi: 10.1038/s41598-017-06970-x. 44. Matia-González, A.M., Iadevaia, V., Gerber, A.P. (2017) A versatile tandem RNA isolation procedure to capture in vivo formed mRNA-protein complexes. Methods, 118-119, 93-100. (epub Oct 13, 2016. ...
Exposed thiol groups do not appear to be related to the binding of 32P-labelled polyribosomes to stripped rough endoplasmic reticulum in vitro. Treating stripped rough endoplasmic reticulum with GSSG did not diminish binding of polyribosomes, suggesting that binding in vitro has no correlation with the inhibition of protein synthesis in vitro reported by Kosower et al. (1971). Thiol reagents, which are known to dissociate ribosomes, did not significantly decrease binding of 32P-labelled polyribosomes to stripped rough endoplasmic reticulum. Denaturing the protein of 32P-labelled polyribosomes or stripped rough endoplasmic reticulum of liver or hepatoma with heat, trichloroacetic acid, or HClO4 did not alter the binding in vitro. Therefore, the practice of measuring the binding of 32P-labelled polyribosomes to stripped rough endoplasmic reticulum in vitro (Shires et al., 1971b) is an unsuitable indicator of biological significance in the intact cell.. ...
TY - JOUR. T1 - Accumulation of polyribosomes in dendritic spine heads, but not bases and necks, during memory consolidation depends on cap-dependent translation initiation. AU - Ostroff,Linnaea E.. AU - Botsford,Benjamin. AU - Gindina,Sofya. AU - Cowansage,Kiriana K.. AU - Ledoux,Joseph E.. AU - Klann,Eric. AU - Hoeffer,Charles. PY - 2017/2/15. Y1 - 2017/2/15. N2 - Translation in dendrites is believed to support synaptic changes during memory consolidation. Although translational control mechanisms are fundamental mediators of memory, little is known about their role in local translation. We previously found that polyribosomes accumulate in dendritic spines of the adult rat lateral amygdala (LA) during consolidation of aversive pavlovian conditioning and that this memory requires cap-dependent initiation, a primary point of translational control in eukaryotic cells. Here we used serial electron microscopy reconstructions to quantify polyribosomes in LA dendrites when consolidation was blocked ...
Treatment of leukemia cells with 1,25-dihydroxyvitamin D3 may overcome their differentiation block and lead to the transition from myeloblasts to monocytes. To identify microRNA-mRNA networks relevant for myeloid differentiation, we profiled the expression of mRNAs and microRNAs associated to the low- and high-density ribosomal fractions in leukemic cells and in their differentiated monocytic counterpart. Intersection between mRNAs shifted across the fractions after treatment with putative target genes of modulated microRNAs showed a series of molecular networks relevant for the monocyte cell fate determination In this dataset, we include the microRNA expression data obtained from the profiling of ribosome/polysome-associated miRNAs and mRNAs in proliferating HL60 cells and in cells induced to differentiate by 1,25-dihydroxyvitamin D3 (VitD3) treatment
The RNA helicase eIF4A1 is a key component of the translation initiation machinery and is required for the translation of many pro-oncogenic mRNAs. There is increasing interest in targeting eIF4A1 therapeutically in cancer, thus understanding how this protein leads to the selective re-programming of the translational landscape is critical. While it is known that eIF4A1-dependent mRNAs frequently have long GC-rich 5′UTRs, the details of how 5′UTR structure is resculptured by eIF4A1 to enhance the translation of specific mRNAs are unknown. Using Structure-seq2 and polysome profiling, we assess global mRNA structure and translational efficiency in MCF7 cells, with and without eIF4A inhibition with hippuristanol. We find that eIF4A inhibition does not lead to global increases in 5′UTR structure, but rather it leads to 5′UTR remodeling, with localized gains and losses of structure. The degree of these localized structural changes is associated with 5′UTR length, meaning that eIF4A-dependent mRNAs
Dept. of Biological Sciences. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1981 .B372. Source: Masters Abstracts International, Volume: 40-07, page: . Thesis (M.Sc.)--University of Windsor (Canada), 1981.
Active transport : Transport of molecules against concentrataion gradient, i.e., from lower to higher concentration with the consumption of energy (ATP). Polyribosome/polysome : A chain like structure formed when several ribosome are attached to a single mRNA. ...
Polysomes are macromolecular complexes made up of multiple ribosomes simultaneously translating a single mRNA into polypeptide chains. Together, the cellular mRNAs translated in this way are referred to translatome. Translation determines a cells overall gene expression profile. Studying translatome leads to a better understanding of the translational machinery and of its complex regulatory pathways. Given its fundamental role in cell homeostasis and division, bacterial translation is an important target for antibiotics. However, there are no detailed protocols for polysome purification from Staphylococcus aureus, the human pathogen responsible for the majority of multi-drug resistance issues. We therefore developed methods for the isolation of active polysomes, ribosomes, and ribosomal subunits, examining the purity and quality of each fraction and monitoring polysomal activity during protein synthesis. These steps are mandatory for the use of purified S. aureus polysomes and ribosomes for
Individual fractions of polysomes were isolated from yeast. Pulse labeling experiments in vivo show constant specific activity of messenger RNA in each polysome peak; this suggests a uniform density of ribosomes per unit length of messenger RNA. In the cell-free incorporating system, the amount of peptide per ribosome unit increased with the size of polysome.. ...
With RiboLace™ you can selectively isolate native and active polyribosomes and prepare your sample for ribosome profiling, as never done before. We offer an innovative solution to monitor protein expression. To receive more information please contact us at [email protected] ...
Mac innes, J W. and Schlesinger, K, "Effects of excess phenylalanine on in vitro and in vivo rna and protein synthesis and polyribosome levels in brains of mice." (1971). Subject Strain Bibliography 1971. 484 ...
Polyadenylated and nonpolyadenylated mRNA were prepared from polysomes and from the postribosomal supernatant of noninduced and DMSO-induced Friend cells. The mRNA preparations were translated in a wheat germ cell-free system and the in vitro synthesized proteins, fractionated by polyacrylamide gel electrophoresis, were compared by fluorography. The electrophoretic analysis shows that four preparations of poly (A) + RNA code for many different peptides and that most of these peptides are present in each of the poly (A) + RNA translation products. However, the electrophoretic patterns of these translation products differ in the relative amounts of peptides comigrating in the gel electrophoresis. After DMSO treatment, Friend cells show significative differences in the polysomal and nonpolysomal mRNA pools. With induction, globin becomes the most abundant product of the polysomal poly (A) + RNA, while the relative amounts of peptides coded by nonglobin polysomal poly (A) + RNA are reduced. In ...
Regarding the biogenesis of peroxisomes various concepts have been postulated. Based on morphological data that demonstrated close spatial relationships between peroxisomes and the ER, Novikoff and Novikoff (44) favored the idea that new peroxisomes are formed by budding and fission from the ER. However, a series of biochemical studies initiated by de Duve and coworkers (36, 51) in the early 1970s, focusing on the biogenetic route of catalase as a peroxisomal marker, did not reveal an ER involvement in the import of catalase. Subsequent findings of Goldman and Blobel (19) and particularly the group of Lazarow and coworkers (52, 54) confirmed this view demonstrating that peroxisomal matrix proteins, such as catalase, urate oxidase, and enzymes of the peroxisomal β-oxidation pathway, are synthesized on free polyribosomes and thus are imported posttranslationally. Accordingly, Goldman and Blobel (19) postulated a model in which peroxisomal matrix proteins are found in nascent peroxisomes, whereas ...
mRNAs surrounded by polysomes are ready for translation into proteins (Warner et al., 1963); these mRNAs are defined as polysomal-mRNAs (Mustroph et al., 2009). The process is affected by various growth conditions or surrounding situations. Microarray analysis is a powerful tool for detecting genome-wide gene expression. Therefore, using polysomal-mRNAs for microarray analysis can reflect the gene translation information (the translatome) under different developmental stages or environmental conditions from eukaryotes. Polysomal-mRNAs can be collected from the polysomal fraction by sucrose-gradient separation for further quantitative PCR or microarray assay. We modified a protocol (Mustroph et al., 2009) for collecting polysomal-mRNAs via sucrose-gradient separation to eliminate monosomal-mRNA contamination from pLAT52:HF:RPL18 Arabidopsis. This transgenic Arabidopsis uses a pollen-specific promoter (ProLAT52) to generate epitope-tagged polysomal-RNA complexes that could be purified with a specific
and a shift of cyclin D1 mRNA from the polysome-associated to free mRNA fraction, indicating that 15d-PGJ2 inhibits the initiation of cyclin D1 mRNA translation. The selective rapid decrease in cyclin D1 protein accumulation is facilitated by its rapid turnover (t1/2=34 min) after inhibition of cyclin D1 protein synthesis. The half-life of cyclin D1 protein is not significantly altered in cells treated with 15d-PGJ2. Treatment of cells with 15d-PGJ2 results in strong induction of heat shock protein 70 (HSP70) gene expression, suggesting that 15d-PGJ2 might activate protein kinase R (PKR), an eIF- ...
A subset of mRNAs, polyribosomes, and poly(A)-binding proteins copurify with microtubules from sea urchin embryos. Several lines of evidence indicate that the interaction of microtubules with ribosomes is specific: a distinct stalk-like structure appears to mediate their association; ribosomes bind to microtubules with a constant stoichiometry through several purification cycles; and the presence of ribosomes in these preparations depends on the presence of intact microtubules. Five specific mRNAs are enriched with the microtubule-bound ribosomes, indicating that translation of specific proteins may occur on the microtubule scaffolding in vivo. ...
Fig. 2. Expression of ribosomal-protein-encoding (RP) mRNAs in yeast cells after the carbon source shift. Each colored square represents the ratio of total mRNA (tot) or high-molecular-weight polysomal mRNA (poly vs. poly; fractions 10 to 14) isolated following incubation in glycerol medium for 5 or 10 min, relative to the amount of the mRNA isolated from cells grown in the presence of glucose. In addition, mRNA abundance in fractions 2 through 6, designated as mRNA protein complexes (mRNP), was compared to the abundance of mRNA present in polysomes (poly vs. mRNP). Black squares denote no significant difference in the amount of RNA isolated from glucose-grown or glycerol-shifted cells; red squares and green squares denote RNAs that are more or less abundant, respectively. The intensity of the color is proportional to the log2 of the fold increase or decrease, with maximal intensity corresponding to an eightfold increase or decrease. For duplicated RP mRNA genes (designated A and B), only data ...
Davidovic L, Bechara E, Gravel M, Jaglin XH, Tremblay S, Sík A, et al. The nuclear microspherule protein 58 is a novel RNA-binding protein that interacts with fragile X mental retardation protein in polyribosomal mRNPs from neurons. Hum Mol Genet. 2006;15(9):1525-38. ...
When cells are subjected to stress, such as heat shock, genes associated with growth are downregulated and expression of proteins believed to increase cellular survival, such as HSP70, are selectively upregulated. In eukaryotes, this regulation operates at multiple levels: transcription initiation may be enhanced via factors specific for heat shock-genes, whereas for other genes there is selective inhibition of splicing and nuclear export of mRNAs (Bond, 2006).. Stress also influences the fate of cytoplasmic mRNA in eukaryotes. Treatment of mammalian cells with a variety of stresses, such as arsenite or heat shock, results in the relocation of most mRNAs from polysomes to cytoplasmic foci called stress granules (Kedersha et al., 1999). These contain the small ribosomal subunit (Kedersha et al., 2002), the translation-initiation factors eIF2, eIF3, eIF4E and eIF4G (Kedersha et al., 2002; Kimball et al., 2003), the poly(A)-binding protein (Kedersha et al., 1999), DHH1 (also known as DDX6, Rck, ...
Redman, C.M.; Banerjee, D.; Manning, C.; Huang, C.Y.; Green, K., 1978: In vivo effect of colchicine on hepatic protein synthesis and on the conversion of proalbumin to serum albumin
The toxin alpha-sarcin specifically cuts 28 S rRNA at a single position 393 nucleotides from its 3 end in isolated rat liver polysomes, provided the ribosomes are pretreated with EDTA or puromycin (Endo, Y. & Wool, I. G. (1982) J. Biol. Chem. 257, 9054-9060). In addition, alpha-sarcin behaves as a purine-specific RNase on deproteinized RNA, cleaving on the 3 side of purines in both single- and double-stranded RNA (Endo, Y., Huber, P. W., and Wool, I. G. (1983) J. Biol. Chem. 258, 2662-2667). Since alpha-sarcin does not readily enter tissue culture cells, we have injected it into Xenopus oocytes in order to determine whether the toxin cleaves after all purines or if it specifically makes a single cut in 28 S rRNA in intact cells. We report here that in oocytes alpha-sarcin specifically cuts 28 S rRNA 377 nucleotides from its 3 end, even when used at concentrations that would degrade deproteinized RNA. alpha-Sarcin does not behave as a general nuclease when injected into Xenopus oocytes nor does it
Protein synthesis is a template polymerization process composed by three main steps: initiation, elongation, and termination. During translation, ribosomes are engaged into polysomes whose size is used for the quantitative characterization of translatome. However, simultaneous transcription and translation in the bacterial cytosol complicates the analysis of translatome data. We established a procedure for robust estimation of the ribosomal density in hundreds of genes from Lactococcus lactis polysome size measurements. We used a mechanistic model of translation to integrate the information about the ribosomal density and for the first time we estimated the protein synthesis rate for each gene and identified the rate limiting steps. Contrary to conventional considerations, we find significant number of genes to be elongation limited. This number increases during stress conditions compared to optimal growth and proteins synthesized at maximum rate are predominantly elongation limited. Consistent with
TY - CHAP. T1 - Best Practices in Evaluating Novel Biomarker Fit for Purpose and Translatability. AU - Baker, Amanda F. PY - 2016/1/1. Y1 - 2016/1/1. N2 - This chapter discusses various tactical aspects to consider when evaluating novel biomarker translatability. The evaluation procedures warrant careful attention in order to leverage the most appropriate traditional and novel biomarkers in the relevant biological matrices. Integration of biomarkers into clinical protocols requires incorporation of biomarker analysis into one of the study objectives. The chapter also describes the use of fit-for-purpose biomarkers in different phases of drug development. When translating a biomarker from preclinical to clinical studies, the species specificity of the assay should be evaluated. Evidence-based protocols for sample collection should be developed and implemented for each biomarker analyzed. When multiple biomarkers are to be analyzed, multiple types of collection containers/tubes may be necessary. ...
Adipogenesis is a complex process, in which immature pre-adipocytes change morphology, micro-anatomy and physiology to become mature adipocytes. These store and accumulate fat and release diverse hormones. Massive changes in protein content and protein composition of the transforming cell take place within a short time-frame. In a previous study we analyzed changes in the abundance of free and polysomal, i.e. ribosome bound, RNAs in the first hours of adipogenesis in the murine cell line 3T3-L1. Here we analyze changes of mRNA levels and their potential contribution to the changing protein pool by determination of mRNA levels and ribosome binding to mRNAs in 3T3-L1 cells stimulated for adipogenesis. We grouped mRNA species into categories with respect to up- or down-regulated transcription and translation and analyzed the groups regarding specific functionalities based on Gene Ontology (GO). A shift towards up-regulation of gene expression in early adipogenesis was detected. Genes up-regulated at the
Les travaux de J. Brachet et de ses collaborateurs sur le rôle des acides nucléiques dans le développement embryonnaire des Amphibiens ont eu pour hypothèses directrices, ces dernières années (Brachet, 1965, 1967 a, b, 1968), que les synthèses protéiniques spécifiques des différentes étapes de la morphogénèse se feraient dans le cytoplasme au niveau des polyribosomes. Les RNA messagers de ces organites existeraient dans lœuf sous des formes stables qui se démasqueraient au moment de la maturation et assureraient les synthèses protéiniques pendant la segmentation; à partir de la gastrulation, ils seraient synthétisés au contact de DNA chromosomiaux déréprimés de façon différentielle par les territoires cytoplasmiques où ils se trouvent. Au gradient ribosomial animal-végétatif de lœuf indivis se superposerait ainsi dans les gastrules un gradient polysomial dorso-ventral, ce double gradient étant léquivalent biochimique des gradients morphogénétiques des ...
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TY - JOUR. T1 - Hepatic protein synthesis rate of liver specimens as a predictor of viability in rat cold ischemia liver transplantation model. AU - Matsui, Yoshifumi. AU - Asano, Takehide. AU - Nakagohri, Toshio. AU - Yokoro, Yoshiharu. AU - Kainuma, Osamu. AU - Kenmochi, Takashi. AU - Isono, Kaich. PY - 1997/11. Y1 - 1997/11. N2 - Background/Aims: We have previously reported that the hepatic protein synthesis rate, calculated as the uptake rate of L-[4.5 3H] leucine by the fraction during a 10-min incubation of a 16-G needle biopsy specimen of liver tissue, represents a high level of liver function and is therefore useful for evaluating liver function. We investigated the hepatic protein synthesis rate level in a pretransplant liver to learn if it might predict the outcome in a rat orthotopic liver transplantation model. Methods: Grafts were stored, liver specimens were obtained using a 21-G Chiba type II skinny needle, and the hepatic protein synthesis rate was calculated. Subsequently, liver ...
TY - JOUR. T1 - Hemoglobin transition in erythrocytes of developing chick. Studies with cell-free protein-synthesizing systems. AU - Henderson, A. Burl. AU - Lee, John C.. PY - 1976. Y1 - 1976. N2 - Cell-free hemoglobin-synthesizing systems from erythrocytes of 4- and 17-day chick embryos have been developed. These systems have been used to investigate possible structural and functional differences in factors involved in protein synthesis obtained from these different developmental stages. Each cell-free system consists of three major cellular fractions i.e., the S-100 supernatant, the salt-washed ribosomes, and the 0.5 m KCl ribosomal wash. When the ribosomal wash fraction from one developmental stage is included in a cell-free system containing ribosomes and S-100 supernatant from the other developmental stage, a drastic reduction in the kinetics of [3H]leucine incorporation into globin products is observed, when compared to the homologous control cell-free systems. A similar depression of the ...
Acute administration of iron to rats has been previously shown to induce liver ferritin synthesis by increasing the translation of inactive cytoplasmic ferritin mRNAs for both heavy (H) and light (L) subunits by mobilizing them onto polyribosomes. In this report rat hepatoma cells in culture are used to explore the relationship of this response to intracellular iron levels. After adding iron as ferric ammonium citrate to the medium, latent ferritin H- and L-mRNAs were extensively transferred to polyribosomes, accompanied by increased uptake of [35S]methionine into ferritin protein. Because total cellular levels of L- and H-mRNA were not significantly changed by exposure to iron, the increased ferritin mRNAs on polyribosomes most probably come from an inactive cytoplasmic pool, consistent with the inability of actinomycin-D and of cordycepin to inhibit iron-induced ferritin synthesis. When deferoxamine mesylate, an intracellular iron chelator, was added after the addition of iron to the medium, ferritin
Synaptoneurosomes were lysed by addition of Triton X-100 (final concentration, 1.2%), deoxycholate to 0.6%, cycloheximide to 100 μg/ml, in 100 mM Tris (pH 7.6) in the presence of RNase inhibitors. The lysates were layered over 1 M sucrose in a polysome buffer (RKB; 0.01 M Tris, pH 7.6/1.5 mM MgCl2/1 mM potassium acetate/2 mM 2-mercaptoethanol), and centrifuged at 400,000 × g for 11 min in a Beckman TL-100 ultracentrifuge. The resultant polysomal pellets were resuspended in 80 mM Tris (pH 8), 80 mM NaCl, 3 mM MgCl2, 1.2% Triton N-101 (RP; 24, 25). Equal amounts of polysomal pellet RNA were layered on a 12-ml, 15-45% continuous sucrose gradient in 20 mM Tris (pH 9), 80 mM NaCl, 3 mM MgCl2, 0.05% 2-mercaptoethanol with 7-10 units RNasin and 1 mg/ml heparin, and centrifuged for 90 min at 41,000 rpm in a SW41 rotor (most non-polyribosome-associated RNAs are thus not included in the gradient). Samples were collected with an ISCO spectrophotometer-coupled gradient fraction collector, diluted with an ...
Self-association of the cardiac fatty acid-binding protein. Influence on membrane-bound, fatty-acid-dependent enzymes: Biochemistry
L35B associates with all pre-60S ribosomal particles. L35B-eGFP was affinity purified from total cellular extracts of Δrpl35B cells expressing L35B-eGFP with G