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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A method is described for indirect electron microscopic visualization and mapping of tRNA and other short transcripts hybridized to DNA. This method depends upon the attachment of the electron-dense protein ferritin to the RNA, the binding being mediated by the remarkably strong association of the egg white protein avidin with biotin. Biotin is covalently attached to the 3' end of tRNA using an NH2(CH2)5NH2 bridge. The tRNA-biotin adduct is hybridized to complementary DNA sequences present in a single stranded non-homology loop of a DNA:DNA heteroduplex. Avidin, covalently crosslinked to ferritin, is mixed with the heteroduplex and becomes bound to the hybridized tRNA-biotin. Observation of the DNA:RNA-biotin:avidin-ferritin complex by electron microscopy specifically and accurately reveals the position of the tRNA gene, with a frequency of labeling of approximately 50%.
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PMID:Electron microscopic visualization of tRNA genes with ferritin-avidin: biotin labels. 34 43

Newts (Triturus cristatus) made anemic with acetylphenylhydrazine (APH) fail to regenerate erythrocytes (RBC's) immediately and exhibit a latent period of 1.5-2 wk during which animals lack RBC's and are aplastic. With the establishment of erythroid regeneration at 10-14 days, relatively homogeneous populations of successive erythropoietic stages occur in the blood. This feature makes possible biochemical analyses of events in early, intermediate, and late developmental stages, respectively, each of which can be obtained in vivo with minimal contamination by other stages. Previous studies have described a primitive cell population referred to as "erythroid precursor cells" (EPC's) which precedes the appearance of definitive erythroid elements. The present studies show that EPC's and early erythroid cells are engaged mainly in ribosomal production, including synthesis of rRNA and ribosomal proteins. Moreover, EPC's and early erythroid cells also synthesize tRNA and a presumed Hb-mRNA which has been identified by its sedimentation rate at 9-12 s and its content of polyadenylic acid. In intermediate stages, there occurs a fourfold decrease in the level of RNA synthesis and, while rRNA continues to be formed, there is a disproportionate accumulation of the two major cytoplasmic rRNA species in favor of the large ribosomal subunit RNA. In late developmental stages, the level of RNA synthesis is markedly diminished with little or no evidence of formation of defined RNA classes. Correlated radioautographic and biochemical studies with radioactive delta-aminolevulinic acid and leucine indicate that EPC's and other early erythroid elements synthesize not only hemoglobin but also ferritin and ribosomal proteins. It is concluded that: (a) erythroid RNA synthesis is most pronounced in the early developmental stages, being manifested predominantly by rRNA production but including tRNA and Hb-mRNA; (b) intermediate developmental stages show both "ribosomal wastage" and decreased growth rate, marking a pivotal point between the transcriptional activities of early stages and translational activities of late stages; (c) EPC's represent a cell population already committed to RBC formation and are excluded from a role as the pluripotential stem cell.
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PMID:Biochemical characterization of RNA and protein synthesis in erythrocyte development. 85 32

In duck erythroblasts, two major populations of untranslated messenger (m) RNP can be separated by sucrose gradient centrifugation in low ionic strength. One of these contains globin mRNA associated to protein factors, among them the prosomes. The other, sedimenting in the 35S zone, contains non-globin mRNA. From this '35S' mRNP, a new RNP particle called the prosome-like particle was isolated and characterized [Akhayat, O., Infante, A. A., Infante, D., Martins de Sa, C., Grossi de Sa, M.-F. & Scherrer, K. (1987) Eur. J. Biochem. 170, 23-33]. The PLP is a multimer of a protein of M(r) 21,000, and contains small RNA species. The particle is tightly associated with repressed mRNA and inhibits in vitro protein synthesis. We show here that the protein of M(r) 21,000, constituting the prosome-like particle, is apoferritin. Different approaches confirm the RNP character of this particle and provide evidence that some of its RNA species are tRNA. The hypothesis is discussed as to whether (apo-)ferritin might serve other functions in addition to iron storage.
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PMID:The protein of M(r) 21,000 constituting the prosome-like particle of duck erythroblasts is homologous to apoferritin. 149 59

A technique that permitted the reversible dissociation of rat liver ribosomes was used to study the difference in protein-synthetic activity between liver ribosomes of normal and hypophysectomized rats. Ribosomal subunits of sedimentation coefficients 38S and 58S were produced from ferritin-free ribosomes by treatment with 0.8m-KCl at 30 degrees C. These recombined to give 76S monomers, which were as active as untreated ribosomes in incorporating phenylalanine in the presence of poly(U). Subunits from normal and hypophysectomized rats were recombined in all possible combinations and the ability of the hybrid ribosomes to catalyse polyphenylalanine synthesis was measured. The results show that the defect in ribosomes of hypophysectomized rats lies only in the small ribosomal subunit. The 40S but not the 60S subunit of rat liver ribosomes bound poly(U). The only requirement for the reaction was Mg(2+), the optimum concentration of which was 5mm. No apparent difference was seen between the poly(U)-binding abilities of 40S ribosomal subunits from normal or hypophysectomized rats. Phenylalanyl-tRNA was bound by 40S ribosomal subunits in the presence of poly(U) by either enzymic or non-enzymic reactions. Non-enzymic binding required a Mg(2+) concentration in excess of 5mm and increased linearly with increasing Mg(2+) concentrations up to 20mm. At a Mg(2+) concentration of 5mm, GTP and either a 40-70%-saturated-(NH(4))(2)SO(4) fraction of pH5.2 supernatant or partially purified aminotransferase I was necessary for binding of aminoacyl-tRNA. Hypophysectomy of rats resulted in a decreased binding of aminoacyl-tRNA by 40S ribosomal subunits.
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PMID:A decreased aminoacyl-transfer-ribonucleic acid-binding capacity of 40S ribosomal subunits resulting from hypophysectomy of the rat. 507 70

Messenger RNA from rat liver was translated in a micrococcal-nuclease-treated reticulocyte lysate supplemented with liver tRNA. Synthesis of the liver proteins haemopexin, ferritin and albumin was analyzed by quantitative immunoprecipitation. The relative translation yield of these proteins changed as a function of the amount of mRNA present during protein synthesis, revealing the existence of translational competition between individual species of mRNA from the liver. The results show that the mRNA species encoding haemopexin, ferritin and albumin possess distinctly different abilities to compete for one or more critical components in translation, with competitive strength increasing in this order. Although on a weight basis total liver mRNA is apparently as effective a template for protein synthesis as is globin mRNA, the latter displays a greater resistance to inhibition of its translation by KCl. In analogy with the translation properties of alpha-globin and beta-globin mRNA [Di Segni, G., Rosen, H. and Kaempfer, R. (1979) Biochemistry, 18, 2847-2854], this finding suggests that globin mRNA possesses greater competitive strength than does total liver mRNA. Increasing amounts of globin mRNA competitively inhibit the translation of albumin and ferritin mRNA present in total liver mRNA. The competition is relieved by the addition of eukaryotic initiation factor eIF-2. Translation of ferritin mRNA responds more vigorously to relief by eIF-2 than does translation of albumin mRNA, a finding consistent with the observation that albumin mRNA competes more effectively than ferritin mRNA in translation. The results support the assumption that albumin mRNA possesses a greater affinity for eIF-2 than does ferritin mRNA.
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PMID:Translational competition by mRNA species encoding albumin, ferritin, haemopexin and globin. 684 65

The influence of copper (Cu) status on hepatic gene expression was examined by using the "messenger RNA differential display" technology. This method involves the distribution of mRNA in a two-dimensional array for the rapid identification and cloning of differentially expressed genes. Livers from male Sprague-Dawley rats that had been fed a Cu-deficient (CD) diet (9.4 micromol/kg) or a Cu-adequate (CA) diet (103.9 micromol/kg) for 6 wk were used to supply cytosolic RNA. Cytosolic RNA were reverse-transcribed in the presence of anchor primers and then amplified by polymerase chain reaction with anchor and arbitrary primer sets. The amplified cDNA were then resolved by denaturing polyacrylamide gel electrophoresis. Differences in mRNA expression between the CD and CA rats were identified. DNA fragments were cloned, sequenced and used as probes for Northern blot analysis to confirm that the identified genes were differentially expressed. The analysis of cDNA sequences by computer searches against DNA and protein databases revealed that one cDNA fragment, whose mRNA abundance was enhanced 1.2-fold by copper deficiency, is novel. Four other cDNA fragments were found to have substantial homology with rat ferritin mRNA; rat fetuin mRNA; rat mitochondrial 12S and 16S rRNA, phenylalanine-, valine- and leucine-tRNA genes; rat mitochondrial genes for 16S rRNA, tRNA-leucine and tRNA-valine; and their mRNA abundance was 0.6- to 0.8-fold higher in Cu-deficient rats. Five additional cDNAs detected by this method appeared to represent novel genes because they exhibited no substantial homology to recorded gene and protein sequences deposited in DNA and protein databases. These results demonstrate the usefulness of this technology in the detection of genes which were differentially expressed as a result of the deprivation of a single nutrient, dietary copper, in this research project.
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PMID:Enhanced expression of hepatic genes in copper-deficient rats detected by the messenger RNA differential display method. 868 38

The first evidence for a plant tRNA(Lys)(CUU) gene is reported. This gene is found closely linked 400 bp upstream, and on the complementary strand, of a ZmFer2 ferritin gene in the maize nuclear genome. Southern blot analysis indicates that this tRNA(Lys) is a member of a multigene family. This gene does not contain any intron, and exhibits classical intragenic regulatory elements found in eukaryotic tRNA genes (A and B boxes). Moreover, 5' and 3'-flanking sequences display typical features found in nuclear encoded tRNAs. The deduced mature tRNA sequence is almost identical to the sequence of a cytoplasmic tRNA(Lys)(CUU) from wheat germ. The maize tRNA(Lys) gene is expressed in vivo in maize and in transgenic tobacco, as shown by RT-PCR analysis.
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PMID:Characterization of a tRNA(Lys)(CUU) gene located in the opposite orientation upstream of a ZmFer2 ferritin gene in the maize nuclear genome. 898 88

Studies employing mRNA transfection are currently limited by a lack of transcription vectors for generating a long poly(A) tail-containing mRNA and published methods for efficient mRNA transfection. We have constructed a transcription vector containing firefly luciferase gene (pBS-FLuc-A100) to generate luciferase mRNA with A100 tail followed by no heterologous sequence. The pBS-FLuc-A100 was propagated in XL1-Blue, in which the plasmid was more stable than in other bacterial strains. Optimal mRNA transfection conditions were determined using TransMessenger Transfection Reagent (Qiagen) and yeast tRNA as a carrier. Firefly luciferase expression, which peaked at about 12 h post-transfection, was detected with as little as 5 ng mRNA and was linear with mRNA amount up to 100 ng. When cells were transfected with luciferase mRNA containing different lengths of poly(A) tail, luciferase expression increased proportionally with poly(A) tail length up to 60A residues and then declined. Cell lines from monkey, mouse, and rat were transfected efficiently by this method. Like cellular ferritin heavy chain mRNA, which contains an iron response element in its 5'UTR, translation of transfected luciferase mRNA containing the 5'UTR of ferritin mRNA was iron-dependent. Our results demonstrate that the poly(A) vector and the transcription method described will be useful to study the regulation of gene expression at the mRNA level by UTRs.
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PMID:Optimized transfection of mRNA transcribed from a d(A/T)100 tail-containing vector. 1580 89

Oxidation of RNA can be effected by two different techniques: a photochemical, electron-transfer method termed "flash-quench" and direct oxidation by metal oxo complexes. The flash-quench method produces selective oxidation using a metal photosensitizer, tris(bipyridyl)ruthenium(III) trichloride (Ru(bpy)(3)(3+)), and quencher, pentaamminechlorocobalt(III) chloride (Co(NH(3))(5)Cl(2+)). We have optimized the flash-quench technique for the following RNAs: tRNA(Phe), human ferritin iron-responsive element (IRE), and a mutated human ferritin IRE. We have also employed a chemical footprinting technique involving the oxoruthenium(IV) complex (Ru(tpy)(bpy)O(2+) (tpy = 2,2',2''-terpyridine; bpy = 2,2'-bipyridine)) to oxidize guanine. Comparison of the two methods shows that the flash-quench technique provides a visualization of nucleotide accessibility for a static conformation of RNA while the Ru(tpy)(bpy)O(2+) complex selectively oxidizes labile guanines and gives a visualization of a composite of multiple conformations of the RNA structure.
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PMID:Nature of guanine oxidation in RNA via the flash-quench technique versus direct oxidation by a metal oxo complex. 2003 24

Among diagnostic progress over the last three years in internal medicine, Antisynthetase Syndrome is now more easily recognised with the diffusion of laboratory tests for research of antibodies against tRNA synthetases (Anti JO1, anti PL7, Anti PL12). In two third of cases, these antibodies are found despite absence of antinuclear antibodies. Hence, we have to search them specifically in patients with polyarthritis associated with myositis, cutaneous manifestations (Raynaud phenomenom and "mechanic'hands") and interstitial lung disease. Discovery of asymptomatic mutation in the L ferritin coding sequence help us to better understand the "unexplained" hyperferritinemia. Initially described by japonese gastroenterologists, auto immune pancreatitis in fact a part of a systemic sclerosing disease with a biochemical hallmark: in crease of a subclass of immunoglobulins G (IgG4). A new pediatric disease due to a deficiency of the interleukin1 receptor antagonist (multifocal aseptic osteitis, periostitis, stomatitis, disseminated pustulosis) help us to better understand unexplained auto inflammatory diseases. The therapeutic progress is primarily due to an explosion of biological therapies, particularly four of them very useful for internists (in an off label use) : Interleukin 1 inhibitors (anakinra, Canakinumab) to treat some auto inflammatory diseases (cryopirin associated periodic syndromes and deficency of interleukin 1 receptor antagonist), monoclonal antibody against interleukin 5 (mepolizumab) to treat some hypereosinophilic syndromes and Churg and Strauss angiitis, interleukin 6 inhibitiors to treat multifocal Castleman's disease and adult Still disease, a monoclonal antibody against vascular endothelial growth factor (Bevacizumab) to treat hereditary hemorrhagic telangiectasia.
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PMID:[What's new in internal medicine?]. 2011 57


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