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

Three human lung tumor-associated antigens (TAA's) have been identified in soluble and membrane-solubilized extracts of human squamous cell lung carcinoma with the use of antisera raised in rabbits. The antigens were identified and partially characterized by means of an agarose adsorption technique. These antigens, termed lung TAA's 1,2, and 3, are all soluble in 50% ammonium sulfate, are antigenically distinct, and do not cross-react with carcinoembryonic antigen or alpha-fetoprotein. Lung TAA's 1 and 2 are oncofetal antigens demonstrable in soluble extracts from 24-week-old but not from 26-week-old fetal lungs. Rabbit antibodies to these lung TAA's were not adsorbed by types A, B, and O human red blood cells, serum proteins as well as soluble or insoluble lung preparations. Of several commercial antisera to human proteins, none cross-reacted with lung TTA 1, but anti-human liver ferritin cross-reacted with lung TAA 2, and anti-human lactoferrin cross-reacted with lung TAA 3. Lung TAA 1 was partially adsorbed and cross-reacted with certain normal serum or plasma preparations used and appears to be a normal serum protein in Cohn Fraction IV-4. Lung TAA 2 and 3 appear only in lung tumor-soluble extracts, whereas the lung TAA 1 was demonstrable in soluble extracts of breast, colon, cervical and head and neck carcinoma. All may be tumor markers of value in immunodiagnosis.
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PMID:Isolation and identification of human lung tumor-associated antigens. 6 79

Horse ferritins from different organs show heterogeneity on electrofocusing in Ampholine gradients. Both ferritin and apoferritin from liver and spleen could be fractionated with respect to surface charge by serial precipitation with (NH4)2SO4. In the ferritin fractions, increasing iron content parallels increasing isoelectric point. After removal of their iron, those fractions which originally contained most iron accumulated added iron at the fastest rates. When unfractionated ferritins from different organs were compared the average isoelectric point increased in order spleen less than liver less than kidney less than heart. The order of initial rates of iron uptake by the apoferritins was spleen greater than kidney greater than heart and initial average iron contents also followed this order. The relatively low rates of iron accumulation by iron-poor molecules may have been due to structural alteration, to degradation, to activation of the iron-rich molecules or to other factors.
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PMID:Heterogeneity in horse ferritins. A comparative study of surface charge, iron content and kinetics of iron uptake. 73 8

We evaluated three methods for isolating ferritin for use as a standard, with respect to purity of the products, ease of preparation, and yield. Examination of the respective products by gel filitration on Sephadex G-200 and Sepharose 6B suggested that the preparations isolated by ammonium sulfate and cadmium sulfate precipitation (Method 1) and by ultracentrifugation (Method 2) were homogeneous, while the product of a procedure including precipitation with ammonium sulfate (Method 3) contained significant amounts of nonferritin protein. The ratios of ferritin as measured by immunoradiometric assay to the amount of protein in the product indicated the ferritin prepared by Method 1 to be the most highly purified. Methods 1 and 2 were both comparatively simple. Although the yield from Method 1 was lowest, it is probably the method of choice, on the basis of the ease of obtaining a highly purified product. The most appropriate method for estimating protein in the isolated preparations appears to be that of Lowry et al.
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PMID:Comparison of three procedures for isolating human ferritin, for use as a standard in an immunoradiometric assay. 125 34

Cell surface hydrophobicity of Mycoplasma hyopneumoniae was evaluated by phase partitioning in a hydrocarbon-aqueous mixture, by hydrophobic interaction chromatography, and by salting out with ammonium sulfate. Results obtained by use of these techniques gave evidence that the cell surface of M hyopneumoniae is weakly hydrophobic, compared with strongly hydrophobic Staphylococcus aureus Cowan I and hydrophilic Klebsiella pneumoniae. After treatment of the organisms with trypsin, M hyopneumoniae became less hydrophobic as measured by hydrophobic interaction chromatography. Significant changes in hydrophobicity were not seen after periodate treatment. Electron microscopy of M hyopneumoniae treated with polycationic ferritin revealed an intermediate, compact, unlabeled layer between the cytoplasmic membrane and an external, heavily labeled layer. Electron microscopy of ferritin-labeled M hyopneumoniae after treatment with trypsin or periodate revealed the intermediate layer to be composed of a trypsin-sensitive protein(s). The outer layer was made of periodate-sensitive carbohydrate(s). Therefore, it appears that proteins in the intermediate layer confer at least part of the total hydrophobicity of the mycoplasmal cell and may contribute to adherence of M hyopneumoniae to target respiratory cells by hydrophobic interactions.
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PMID:Morphologic features and hydrophobicity of the cell surface of Mycoplasma hyopneumoniae. 132 25

We have examined the distribution of ferritin mRNA to free and endoplasmic reticulum (ER)-bound liver polyribosomes during inflammation and iron treatment of rats. Postnuclear tissue supernatants were fractionated on a discontinuous sucrose gradient developed to separate free and bound polyribosomes. Total RNA recovered averaged 3.2 mg/g tissue, 40% of which was with ER and 30% with the free polyribosomes, about 25% being with the postribosomal/RNP fraction. Slot-blot hybridization of equal portions of RNA revealed that 12 h after injection of turpentine to induce inflammation, ferritin mRNA was concentrated on the ER-bound polyribosomes, while it was concentrated on the free polyribosomes 2 h after injection of ferric ammonium citrate. Differences were highly significant, based on multiple determinations and densitometry. Profiles of ferritin mRNA distribution on linear sucrose gradients corroborated the differential findings. Concentrations of total ferritin mRNA per gram liver doubled with iron treatment but were not significantly different 12 h after turpentine treatment. At the same time point after turpentine, ferritin protein synthesis was increased twofold, as measured by the 1 h incorporation of [14C]leucine. We conclude that a significant portion of ferritin mRNA always associates with the ER-bound polyribosomes, and that inflammation and iron differentially alter the polysomal distribution of ferritin mRNA, suggesting that two different kinds of mRNA may be involved.
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PMID:Differential effects of iron and inflammation on ferritin synthesis on free and membrane-bound polyribosomes of rat liver. 144 58

This study compared the effect of loading apoferritin either with ferrous ammonium sulfate in various buffers or with ceruloplasmin and chelated ferrous iron. It was shown that loading of apoferritin with ferrous ammonium sulfate was dependent on buffer and pH, and was directly related to the rate of iron autoxidation. The ceruloplasmin-dependent loading of apoferritin, however, was unaffected by these factors. Isoelectric focusing and amino acid analysis of the differently loaded ferritins showed that ferrous ammonium sulfate loading of apoferritin resulted in the depletion of the basic amino acids, lysine and histidine, probably as a result of protein oxidation. No significant differences in amino acid composition was noted for ceruloplasmin-loaded ferritin. Furthermore, ferritin loaded with ferrous ammonium sulfate released more iron than either native or ceruloplasmin-loaded ferritin when either paraquat or EDTA was used as an iron mobilizing agent. We suggest that the loading of apoferritin with ferrous ammonium sulfate occurred as a result of iron autoxidation and may result in oxidation of amino acids and loss of integrity of the protein, and that ceruloplasmin may act as a catalyst for the incorporation of iron into apoferritin in a manner more closely related to that occurring in vivo.
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PMID:In vitro loading of apoferritin. 153 76

The mechanisms that regulate the expression of the H chain of the iron storage protein ferritin in Friend erythroleukemia cells (FLCs) after exposure to hemin (ferric protoporphyrin IX), protoporphyrin IX, and ferric ammonium citrate (FAC) have been investigated. Administration of hemin increases the steady-state level of ferritin mRNA about 10-fold and that of ferritin protein expression 20-fold. Experiments with the transcriptional inhibitor actinomycin D and transfection studies demonstrate that the increment in cytoplasmic mRNA content results from enhanced transcription of the ferritin H-chain gene and cannot be attributed to stabilization of preexisting mRNAs. In addition to transcriptional effects, translational regulation induces the recruitment of stored mRNAs into functional polyribosomes after hemin and FAC administration, resulting in a further increase in ferritin synthesis. Administration of protoporphyrin IX to FLCs produces divergent transcriptional and translational effects. It increases transcription but appears to suppress ferritin mRNA translation. FAC treatment increases the mRNA content slightly (about twofold), and the ferritin levels rise about fivefold over the control values. We conclude that in FLCs, hemin induces ferritin H-chain biosynthesis by multiple mechanisms: a transcriptional mechanism exerted also by protoporphyrin IX and a translational one, not displayed by protoporphyrin IX but shared with FAC.
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PMID:Modulation of ferritin H-chain expression in Friend erythroleukemia cells: transcriptional and translational regulation by hemin. 162 Jan 12

While iron is essential for numerous intracellular processes, its critical role in DNA synthesis relates to the activity of the iron-containing M2 subunit of ribonucleotide reductase, the enzyme responsible for the synthesis of deoxyribonucleotides. Gallium, a metal which resembles iron with respect to transferrin (Tf) binding, cellular uptake by the Tf receptor and incorporation into ferritin, blocks the cellular uptake of iron and inhibits cell growth. Exposure of HL60 cells to Tf-gallium (Ga) results in decreased deoxyribonucleotide synthesis and a diminution in the electron spin resonance (ESR) spectroscopy signal of ribonucleotide reductase, findings consistent with inhibition of this enzyme. In the present study, Ga nitrate blocked the uptake of 59Fe by L1210 cells and inhibited their proliferation. The ribonucleotide reductase M2 subunit ESR signal in cell cytoplasmic extracts was markedly inhibited in Ga-treated cells; however, the signal was restored to normal within 10 min of exposure of these cytoplasmic extracts to ferrous ammonium sulfate. These results confirm that Ga inhibits DNA synthesis by specifically limiting the amount of intracellular iron needed for the activity of the M2 subunit of ribonucleotide reductase. Further studies utilizing HL60 cells made resistant to Ga showed that these cells were also more resistant to growth inhibition by an anti-Tf receptor monoclonal antibody and deferoxamine. Ga blocks cell growth through inhibition of iron-dependent DNA synthesis. Cells appear to overcome the effects of Ga through compensatory mechanisms involving cellular iron metabolism.
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PMID:Targeting iron-dependent DNA synthesis with gallium and transferrin-gallium. 164 76

Studies were undertaken using human duodenal mucosa to determine whether it contained a counterpart to a newly identified iron-binding protein recently isolated from rat duodenum and named mobilferrin. Water-soluble homogenates were prepared from duodena of patients undergoing surgery for pancreatic carcinoma. An iron-binding protein with an approximate molecular mass of 56 Kd was purified to homogeneity using 60% ammonium sulfate and serial chromatographic steps. The protein was biochemically and immunologically distinct from transferrin and ferritin, and competitively bound to zinc, cobalt, and lead. Each molecule bound one molecule of iron with a kd of 8.9 x 10(-5). Human isolates reacted in an enzyme-linked immunosorbent assay with a polyclonal antibody raised in rabbits against a similar duodenal protein isolated from rat duodenum. It is postulated that mobilferrin plays a significant role in the absorption of iron and other metals and may explain partially the competition between certain metals for absorption in the small intestine.
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PMID:Newly identified iron-binding protein in human duodenal mucosa. 172 12

Ferritin in macrophages from human liver and spleen is rich in L subunits but, in the peripheral blood monocytes from which tissue macrophages are derived, the ferritin contains a high proportion of H subunits. We have studied the maturation of monocytes in vitro and the immunological properties of cellular ferritin during this process. Mononuclear cells were isolated from peripheral blood of normal subjects and patients with idiopathic haemochromatosis. Monocytes were obtained by incubation on plastic. The adherent cells were incubated in medium with or without added iron (ferric ammonium citrate) for 20 hours and harvested. Monocytes were also incubated for 7 days before incubation with iron. Ferritin concentrations were determined using immunoassays specific for H and L rich isoferritins. Freshly isolated monocytes were found to have similar concentrations of H- and L-rich isoferritins. Incubation with iron caused an increase in both H- and L-type ferritins. After incubation for 7 d the ferritin present in the normal cell lysates was L-rich and incubation with iron caused accumulation of L-, but not H-type ferritin. Maturation of monocytes is thus associated with the loss of H-rich isoferritins. There were no differences between normal subjects and patients with idiopathic haemochromatosis in ferritin concentrations. In vitro maturation provides an excellent model for studying the developmental control of ferritin synthesis and breakdown.
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PMID:Immunological properties of ferritin during in vitro maturation of human monocytes. 191 6


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