Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recent studies reported that iron salts were absorbed in the duodenum utilizing a pathway involving membrane-associated integrin and a cytosolic protein named mobilferrin. In addition, a large molecular weight cytoplasmic complex was labeled with radioiron during mucosal uptake of iron in the duodenum. The molecular mass of this protein was 520 000 daltons, slightly larger than ferritin. On denaturing SDS-PAGE, the purified protein complex appeared to consist of at least four polypeptides, closely associated with each other. This complex was called paraferritin because its hydrodynamic volume resembled ferritin. In the present work, antibody studies demonstrate the presence of integrin, mobilferrin, and flavin monooxygenase in the water-soluble complex. Biochemical studies demonstrate the presence of a NADPH-dependent flavin monooxygenase ferrireductase activity that reduces Fe(III) to Fe(II). Antibodies against either integrin or mobilferrin inhibit monooxygenase activity. Inhibition of monooxygenase activity decreases radioiron uptake by tissue culture intestinal cells. Thus, we postulated that paraferritin plays a role in the mucosal uptake and transport of inorganic iron in small intestinal absorptive cells and is a mechanism for both the internalization of integrin from membranes to cellular cytosol and the delivery of iron to cellular constituents in an appropriate redox state.
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PMID:Paraferritin: a protein complex with ferrireductase activity is associated with iron absorption in rats. 863 93

We describe a method for the purification of ferritin from Musca domestica larval hemolymph. Musca ferritin occurs in hemolymph predominantly as a native protein with molecular weight equal to 550,000 and subunits of 26,000. The average iron content of purified ferritin was determined to be 3,000 +/ 600 iron atoms per molecule. The iron contents of ferritin was heterogeneous; both fully iron loaded molecules and apoferritin are probably present in the Musca hemolymph. The anti-ferritin serum raised in rabbit was able to recognize native ferritin but was not reactive with the protein subunits isolated by SDS-PAGE. The ferritin concentration in hemolymph attains a maximum of 0.28 mg/ml in the wandering stage larvae decreasing to 0.13 mg/ml at the middle of pupal stadium. The ferritin contents of midgut and fat bodies were also determined. Fat body ferritin content is greatly reduced when the feeding larva passes into wandering stage.
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PMID:Musca domestica hemolymph ferritin. 878 19

Ouchterlony double immunodiffusion clearly demonstrated absence of ferritin, the principal iron storage protein, in spleen and/or liver extracts from nine patients with Niemann-Pick disease type C (NPC). The patients died from different clinical forms of this disease of still unknown etiology. The absence of ferritin immunoreactivity was shown using two different antisera raised in rabbits against ferritin from human spleen or liver, organs which predominantly contain light chain subunits (L-ferritin). A diagnostic double immunodiffusion assay of ferritin is, therefore, feasible with small amounts of NPC liver tissue, e.g., needle biopsy specimens. Furthermore, SDS-polyacrylamide gel electrophoresis after Coomassie blue staining revealed an almost complete absence of the L-ferritin protein band in crude spleen heat extracts from two NPC patients. The absence of visceral ferritin in all nine patients studied is suggestive of a biochemical abnormality that is as characteristic as the known impairment of cellular trafficking of LDL-derived cholesterol in this complex lysosomal storage disorder. According to recent data a relationship exists between ferritin-dependent lipid peroxidation and oxidative modification of LDL. We suggest that deficiency of the antioxidant ferritin-whatever the nature of this deficiency might be-could lead to uncontrolled LDL oxidation with subsequent multisubstrate lipidosis in NPC disease.
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PMID:Ouchterlony double immunodiffusion method demonstrates absence of ferritin immunoreactivity in visceral organs from nine patients with Niemann-Pick disease type C. 881 37

Ferritin from alfalfa (Medicago sativa) seeds was isolated, purified, and characterized. The apparent molecular mass of the native protein was found to be 560 kDa. Electrophoresis in denaturing gradient polyacrylamide-SDS gels revealed subunits of 28-26.5 kDa. The average iron cores were 4 nm in diameter and contained about 1400 iron atoms, with an iron-to-phosphorus ratio of 4:1. N-terminal amino acid sequencing of the 28 kDa subunit revealed close homology with other plant proteins. Immunochemical analysis using polyclonal antibodies raised against pea-seed ferritin has confirmed, in agreement with previous reports, that plant proteins share common epitopes.
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PMID:Purification and characterization of ferritin from alfalfa seeds. 907 71

We have reported previously that the heavy chain of ferritin is required for iron incorporation by ceruloplasmin (J.-H. Guo, M. Abedi, and S. D. Aust (1996) Arch. Biochem. Biophys. 335(1)). The purpose of this study was to determine how many heavy chains were required for ceruloplasmin to interact with ferritin such that iron loading occurred. The cDNA sequences encoding the heavy and light chains of rat liver ferritin were cloned into the baculovirus transfer vector pA-cUW51 under the control of polyhedrin and p10 promoters, respectively, which was then incorporated by homologous recombination into the infections Autographa californica nuclear polyhedrosis virus genome. Both ferritin chains were expressed and assembled into two heteropolymers following the infection of insect cells by recombinant virus, which were separated by DEAE-Sepharose chromatography. The percentage of heavy (H) and light (L) chains making up the two heteropolymers, determined by gel scanning following the resolution of chains on SDS-PAGE, were equivalent to 1 H and 23 L chains and 2 H and 22 L chains. The maximal extent of iron loading was observed using 1 mol of rat ceruloplasmin per mole of H chain in the two heteropolymers. The extent of iron incorporation decreased with additional ceruloplasmin. Iron incorporation into rat liver ferritin, found to contain 10 H chains, increased as the molar ratio of ceruloplasmin to ferritin increased to 4:1 and remained the same up to 8:1. Iron loading into horse spleen ferritin, found to have one H chain, appeared similar to that for recombinant ferritin, having only one H chain. Therefore, we propose that the optimal molar ratio of ceruloplasmin to ferritin depends upon the numbers of H chain making up the ferritin molecule for the maximal incorporation of iron into ferritin. These results also suggest that the iron loading channel is contained within a single H chain subunit.
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PMID:Loading of iron into recombinant rat liver ferritin heteropolymers by ceruloplasmin. 916 16

Ferritin mRNAs are translationally regulated by the binding of either of two cytosolic proteins, iron regulatory protein 1 (IRP1) or IRP2, to the iron responsive element (IRE) located in their 5' untranslated region (UTR). Rat liver IRP1 was purified by anion exchange, gel filtration, and affinity chromatography using a concatemerized version of the IRE. Two bands with M(r) of 95,000 and 100,000 were observed by reducing SDS-PAGE. A single protein was responsible for both bands since: (1) [32P]IRE RNA specifically cross-linked to both components; (2) alkylation with iodoacetamide resulted in formation of a single species with M(r) of 95,000; and (3) they possessed identical peptide patterns after digestion with cyanogen bromide. The N-terminal sequence of rat liver IRP1 was MKNPFAHLAEPLDPAQPGKKFNLNKLEDSRYGRLPFXIRVLLEAAV which is identical to the sequence deduced from the cDNA. Rat liver IRP1 has an amino acid composition similar to that of bovine liver caconitase. Several species of IRP1 were observed by two-dimensional gel electrophoresis with pIs ranging from 7.5 to 8.0. Rat liver IRP1 bound the IRE with high affinity (K(D) = 0.04 nM) and repressed translation of ferritin mRNA in vitro. IRP1 bound 100-fold less well to an IRE variant and failed to significantly repress translation of a ferritin mRNA containing the mutated IRE. We conclude that decreases in the affinity of interaction between IRP1 and the IRE, of a magnitude similar to that observed when the binding protein in converted to c-aconitase, are sufficient to significantly enhance translation of ferritin mRNA in vitro.
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PMID:Isolation, characterization, and functional studies of rat liver iron regulatory protein 1. 921 Jun 49

Ferritin was purified from iron-fed Drosophila melanogaster extracts by centrifugation in a gradient of potassium bromide. On polyacrylamide gel electrophoresis, the product showed two protein bands corresponding to the ferritin monomer and dimer. Electrophoresis following dissociation with SDS and 2-mercaptoethanol revealed three strong bands of approximately 25, 26, and 28 kDa. N-terminal amino acid sequences were identical for the 25-kDa and 26-kDa subunits, but different for the 28-kDa subunit. Conserved ferritin PCR primers were used to amplify a 360-bp cDNA product, which was used to isolate a clone from a D. melanogaster cDNA library that contained the complete coding sequence for a ferritin subunit. Additional 5' sequence obtained by the RACE method revealed the presence of a putative iron regulatory element. The PCR product was also used to locate the position of the ferritin subunit gene at region 99F on the right arm of the third chromosome. The deduced amino acid sequence of the D. melanogaster ferritin subunit contained a signal sequence and resembled most closely ferritin of the mosquito Aedes aegypti. The evolution of ferritin sequences is discussed.
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PMID:Isolation and properties of Drosophila melanogaster ferritin--molecular cloning of a cDNA that encodes one subunit, and localization of the gene on the third chromosome. 926 86

In order to investigate how endogenous iron can be deposited in vivo on inhaled mineral fibers during early stages of formation of asbestos bodies, in vitro experiments were performed on the adsorption of ferritin onto amosite asbestos. The mineral dust was found to adsorb the protein from an aqueous solution containing 0.3 mg/ml horse spleen ferritin. In order to simulate physiological conditions the aqueous solution was adjusted with 150 mM saline. Polyacrylamide-SDS gel electrophoresis of the desorbed protein showed subunits of approximately 13 and 15 kD, aside from the 20-kD subunit present in the native protein. This suggests that as a result of interactions between ferritin molecules and the solid surface of the mineral fibers, the protein iron core may be released or partially exposed. Data indicate these interactions may have implications in the observed mineral fiber toxicities.
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PMID:Ferritin adsorption on amosite fibers: possible implications in the formation and toxicity of asbestos bodies. 935 79

The molecular weight of the liver-type subunit (L) of bovine ferritin is much larger than that of the heart-type subunit (H) as determined by SDS-PAGE (L, 20.5 kDa; H, 18.4 kDa). The migration of these two subunits on SDS-PAGE gels, relative to each other, is opposite to that reported for ferritin L and H subunits in other mammalian species (L, 19 kDa; H, 21 kDa). To determine the cause of this anomaly, full-length cDNA clones of the bovine L and H chains were isolated from a bovine spleen gamma gt11 cDNA library and sequenced. The amino acid sequences of the L and H chains of bovine ferritin, deduced from their cDNA sequences, contained open reading frames coding for 174 and 180 amino acid residues with calculated molecular weights of 19,856 and 20,920 Da, respectively. The deduced amino acid sequence of the L chain shows 86%, 84%, 87%, 83% and 83% homology with the amino acid sequences of horse, human, rabbit, rat and mouse L chains, respectively. The H chain displays a higher homology with the human, rat and mouse H chains (91%, 92% and 93%, respectively). In addition, the bovine L chain did not contain the extra octapeptide present in rodent L chains, and bovine, L and H chains did not react with concanavalin A. The bovine L and H chains expressed using a baculovirus expression system showed almost the same mobilities as those of bovine spleen ferritin, respectively, by SDS-PAGE. These results suggest that the much slower mobility of the bovine L chain compared with other mammalian L chains on SDS-PAGE cannot be attributed to insertion(s) of amino acid(s) or peptide(s) into the L chain, to the deletion(s) of them of it or to the addition of carbohydrate chains(s) but may result from significant differences in the binding affinity of SDS for bovine ferritin L chains.
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PMID:Sequencing of cDNA clones that encode bovine ferritin H and L chains. 946 78

The thermal inactivation of horse spleen ferritin was studied over a range of temperatures (36-52 degrees C) in 0.1 M acetate buffer (pH 4.2) as a decrease of its peroxidase activity during tetramethylbenzidine (TMB) oxidation by hydrogen peroxide. The activation energy of this process was 163.3 kJ/mole. Thermodynamic activation parameters for the loss of peroxidase activity of ferritin were calculated. The influence of various detergents on ferritin-dependent oxidation of TMB, ortho-tolidine, and ortho-phenylenediamine (PDA) by hydrogen peroxide was studied in 0.1 M phosphate buffer (pH 6.0) at 20 degrees C. Relatively high concentrations of charged detergents (SDS and cetyltrimethylammonium bromide) decreased the peroxidase activity of ferritin with all three amines, whereas moderate concentrations of the nonionic detergent Triton X-100 did not influence oxidation of these substrates. Increase of dimethylformamide concentration in 0.02 M acetate buffer (pH 4.2) from 5 to 40% strongly decreased the rate of TMB and PDA oxidation by hydrogen peroxide or cumene hydroperoxide. Decrease in the activity of thermally inactivated ferritin with TMB as substrate, reduction of alpha-helical content of the protein at 40-50 degrees C, an inactivating effect of charged surfactants and organic co-solvent on the peroxidase activity of ferritin indicate a very important role of the apoprotein in peroxidase function. A possible mechanism of apoferritin participation in peroxidase catalysis is discussed.
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PMID:Role of the apoprotein in the catalytic peroxidase-like function of ferritin. 948 74


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