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)

Rat liver homogenates in 0.1 M Tris, pH 7.5, were heated to 80 degrees C, cooled immediately, and centrifuged at 24,000 X g, and 7Be2+ was added to the supernatant. Twenty-five per cent of the radioactivity was bound to a single protein. It was purified to homogeneity and identified to be ferritin as judged by different criteria. These were sucrose density gradient centrifugation, electrophoresis in polyacrylamide gel of the native or sodium dodecyl sulfate-treated protein, reactivity to antibodies, isoelectric focusing, and total amino acid composition. Comparative study of the ability of ferritin or apoferritin to bind Cd2+, Zn2+, Cu2+, and Be2+ was conducted by using a gel equilibrium technique, Centifree micropartition technique, and microcentrifuge desalting technique. Ferritin could be saturated with Cd2+ or Zn2+ or Cu2+ but not with Be2+ even after 800 g atoms of Be2+ were bound. None of the bound Be2+ was dialyzable at 4 degrees C in 0.05 Tris acetate buffer, pH 8.5, but at pH 6.5 over 80% of the bound metal ion was dialyzed after 72 h. By contrast, apoferritin bound similar amounts of all four metal ions, some of which were dialyzable. By spectrophotometric titrations at pH 6.5 of Be2+ with sulfosalicylic acid (SSA), BeKDSSA was calculated to be 5.0 X 10(-6) M and by competition of sulfosalicyclic acid and ferritin for Be2+ the BeKDferritin was calculated to be 6.8 X 10(-6) M.
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PMID:Ferritin. Binding of beryllium and other divalent metal ions. 641 22

Ferritin was isolated from the spleen of sheep and found to contain an iron/protein content of 21 per cent. Electrophoretic behaviour on 6 per cent polyacrylamide gel revealed three protein bands of Rf values of 5.7, 19.3 and 76.1. Sheep ferritin has a molecular weight of about 475,000 daltons and is high in glutamic acid, leucine and aspartic acid and low in methionine and cysteine. Sheep ferritin is not crystallisable by 10 per cent cadmium sulphate and has an ultraviolet-visible spectrum similar to that of bovine ferritin. Anti (sheep) ferritin antibodies raised in rabbits showed a 57.1 per cent binding at a serum dilution of 1:800 and 30 per cent binding at a 1:12,800 dilution, in a titre determination using double antibody assay procedure.
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PMID:Isolation of sheep spleen ferritin. 647 7

This paper describes studies on the source, preparation, characterization and storage of human ferritin for use as a standard for the immunoassay of serum ferritin. Ferritin was prepared from the liver or spleen by methods including either ultracentrifugation or cadmium sulphate crystallization. Preparations were characterized by polyacrylamide gel electrophoresis in dissociating and non-dissociating buffers, iso-electric focusing, analysis of amino acid composition and measurement of protein content. The protein content of solutions of liver or spleen ferritin may be determined by the method of Lowry with bovine serum albumin as standard. Lyophilization under carefully controlled conditions in buffer containing high concentrations of albumin provides a stable preparation of ferritin. Accelerated degradation and collaborative immunological studies of two lyophilized preparations of ferritin, one from liver and one from spleen, indicate that either is an acceptable reference material.
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PMID:Preparation, characterization and storage of human ferritin for use as a standard for the assay of serum ferritin. International Committee for Standardization in Haematology (Expert Panel on Iron). 648 40

Metabolic balance for lead and cadmium were carried out in 23 healthy elderly people aged 69.7 to 85.5 yr while living in their own homes and eating self-selected diets. Mean intakes of lead and cadmium were 54.6 and 8.6 micrograms/day, with mean retentions of -8.7 and -1.7 micrograms/day, respectively. Daily dietary lead correlated (p less than 0.05) with the intake of energy, nitrogen, calcium, iron, and zinc but not with manganese or copper. Dietary intake of cadmium correlated (p less than 0.05) only with that of zinc and manganese. There was a highly significant (p less than 0.001) inverse correlation between the percentage cadmium absorbed and body iron stores measured as serum iron, percentage iron saturation, and ferritin. Mean whole blood concentrations were 138 micrograms/l for lead and 0.79 microgram/l for cadmium. The negative balances observed in these elderly people were very different from the positive balances found in a previous similar study in children.
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PMID:The intake and excretion of lead and cadmium by the elderly. 671 83

Various precipitating agents were examined in order to crystallize horse heart and spleen ferritins. Cadmium sulfate induced the crystallization of the spleen ferritin, while 2-methyl-2,4-pentanediol and poly(ethylene glycol) only induced that of the heart ferritin. Isoelectric focusing analysis showed that the crystals grown from cadmium sulfate contained only the more acidic isoferritins, and those grown from methyl pentanediol only the less acidic isoferritins. Heart ferritin crystallizes in a cubic space group, as previously reported for spleen ferritin crystals grown from cadmium sulfate.
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PMID:Selective crystallization of horse isoferritins. 683 99

Non-transferrin-bound iron (NTBI) plays an important role in the hepatocellular injury induced by iron overload. However, the mechanism responsible for NTBI uptake into hepatocytes remains poorly defined. The purpose of this study was to define the kinetics of NTBI uptake by isolated rat hepatocytes and to characterize the uptake process. NTBI uptake was time and temperature dependent, exhibited a Michaelis-Menten constant (Km) value of 1.25 microM and maximum uptake of 241 pmol.10(6) cells-1.min-1, and 55Fe was incorporated in part into intracellular ferritin. Uptake was Ca2+ dependent, exhibiting 15 and 80% of maximal uptake in the presence of 0.6 and 0.75 mM CaCl2, respectively. The putative NTBI transporter was highly specific; divalent (Zn2+, Mn2+, Cd2+, and Co2+) or trivalent (La3+) cations did not inhibit Fe3+ uptake. Reduction from Fe3+ to Fe2+ was not essential for uptake or the process occurred deep within the membrane bilayer, since the Fe2+ chelator ferrozine did not influence 55Fe uptake. These data provide evidence for a low Km plasma membrane transporter for NTBI, which should be functional at physiological serum concentrations and saturated in iron-overload diseases, such as hemochromatosis.
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PMID:Evidence for a low Km transporter for non-transferrin-bound iron in isolated rat hepatocytes. 748 9

Measurements of intake and uptake of cadmium in relation to diet composition were carried out in 57 nonsmoking women, 20-50 years of age. A vegetarian/high-fiber diet and a mixed-diet group were constructed based on results from a food frequency questionnaire. Duplicate diets and the corresponding feces were collected during 4 consecutive days in parallel with dietary recording of type and amount of food ingested for determination of the dietary intake of cadmium and various nutrients. Blood and 24-hr urine samples were collected for determination of cadmium, hemoglobin, ferritin, and zinc. There were no differences in the intake of nutrients between the mixed-diet and the high-fiber diet groups, except for a significantly higher intake of fiber (p < 0.001) and cadmium (p < 0.002) in the high-fiber group. Fecal cadmium corresponded to 98% in the mixed-diet group and 100% in the high-fiber diet group. No differences in blood cadmium (BCd) or urinary cadmium (UCd) between groups could be detected. There was a tendency toward higher BCd and UCd concentrations with increasing fiber intake; however, the concentrations were not statistically significant at the 5% level, indicating an inhibitory effect of fiber on the gastrointestinal absorption of cadmium. Sixty-seven percent of the women had serum ferritin < 30 micrograms/l, indicating reduced body iron stores, which were highly associated with higher BCd (irrespective of fiber intake). BCd was mainly correlated with UCd, serum ferritin, age, anf fibre intake. UCd and serum ferritin explained almost 60% of the variation in BCd.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Intestinal absorption of dietary cadmium in women depends on body iron stores and fiber intake. 771 18

The binding of Cd2+, Zn2+, Cu2+, Ni2+, Co2+, Mn2+, and Mg2+ to apo, holo, reconstituted horse spleen ferritin (HoSF), and native holo HoSF with phosphate removed was measured by gel-exclusion chromatography. Three classes of strong binding interactions (Kd < 10(-7) M) with apo HoSF at pH 7.5 were found for the various M2+ studied: high stoichiometric binding (30-54 M2+/HoSF) for Cd2+, Zn2+, Cu2+, with two protons released per metal bound; intermediate binding (16 M2+/HoSF) for Ni2+ and Co2+, with one proton released per metal bound; and low levels of binding (2-12 M2+/HoSF) for Mn2+, Mg2+, and Fe2+, with < 0.5 protons released per metal bound. M2+ binding to apo HoSF was nearly abolished at pH 5.5, except for Fe2+ and Cu2+, which remained unaffected by pH alteration. Holo HoSF bound much higher levels of M2+, a result directly attributable to the presence of phosphate binding sites. This conclusion was confirmed by decreased binding of M2+ to HoSF reconstituted in the absence of phosphate and by native holo HoSF with phosphate chemically removed. The binding of Cd2+ to apo HoSF was 54 per HoSF, but in the presence of developing core, the amount bound decreased to about 30 Cd2+/HoSF. This result indicated that Cd2+ and developing core were competing for the same sites on the HoSF interior, suggesting that 24 of the Cd2+ were bound to the inside surface. No other M2+ studied bound to the interior of HoSF by this criterion. Several of the M2+ appeared to bind strongly to the phosphate-free mineral core surface in reconstituted HoSF.
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PMID:Metal ion binding to apo, holo, and reconstituted horse spleen ferritin. 778 91

Itai-itai disease is a condition caused by long-term exposure of the inhabitants of Toyama prefecture, Japan, to cadmium intoxication. The characteristic clinical features of this disease include renal tubular dysfunction, osteomalacia, and anemia. In order to clarify the pathogenesis of the anemia, the red blood cell count, hemoglobin concentration, hematocrit, serum iron level, total iron-binding capacity, serum ferritin level, serum erythropoietin level, creatinine clearance, fractional excretion of beta 2-microglobulin, and bone marrow morphology were determined in ten patients with Itai-itai disease. Low serum iron or ferritin levels were not observed, and bone marrow aspiration did not reveal any specific hematological disorders. A close relationship was observed between the decrease in the hemoglobin level and the progression of renal dysfunction. Low serum erythropoietin levels were detected despite the presence of severe anemia. These results suggest an important role of renal damage in the anemia which develops in Itai-itai disease.
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PMID:Hypoproduction of erythropoietin contributes to anemia in chronic cadmium intoxication: clinical study on Itai-itai disease in Japan. 785 2

A transferrin-independent iron transport system in cells containing transferrin receptors was described previously by several investigators. Prior studies did not identify the proteins involved in this alternate iron transport pathway. Using a human-derived erythroleukemia tissue culture line, iron-binding proteins were isolated from cytosol and cell membranes. The cytosol protein was soluble in 60% ammonium sulfate, had a molecular mass similar to mobilferrin (56 kDa), and reacted with anti-mobilferrin antibodies. The water-insoluble radiolabeled protein was solubilized with Nonidet P-40 and immunoprecipitated with monoclonal antibody against beta 3 human integrin. Pulse-chase studies suggested sequential passage of iron to integrin, mobilferrin, and ferritin, respectively. Thus, the alternate iron transport pathway contained proteins similar to those observed in intestinal cells which did not possess transferrin receptors on their absorptive surface. The alternate iron transport pathway is only partially shared with zinc and cadmium. Mobilferrin bound zinc and iron competitively, but the two metals were not transported competitively into K562 cells. Immunoprecipitates of integrin containing radiozinc were obtained with a monoclonal antibody against beta 1 human integrin. This suggested iron and zinc may utilize different integrins to passage the cell membrane.
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PMID:Alternate iron transport pathway. Mobilferrin and integrin in K562 cells. 812 27


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