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

Red cell ferritin was measured in normal subjects and patients with disorders of iron metabolism, inflammation, liver dysfunction, impaired hemoglobin synthesis, and increased red cell turnover by means of radioimmunoassays with antibodies to liver (basic) and heart (acidic) ferritins. The normal mean values for basic and acidic ferritin were 8.9 and 22.7 altogram (ag)/cell, respectively. The red cell ferritin content reflected changes occurring in tissues both in iron deficiency and iron overload. Basic ferritin was more closely related to the body iron status than acidic ferritin, and the acidic/basic ferritin ratio was increased in iron deficiency and decreased in iron overload. The major factor determining the red cell ferritin content appeared to be the transferrin saturation, that is, the distribution of iron between monoferric and diferric transferrin. This is in keeping with recent data indicating a competitive advantage of diferric transferrin in delivering iron to erythroid cells. In addition, the red cell ferritin content was increased in thalassemic patients with normal iron status, appearing to be inversely related to the rate of hemoglobin synthesis. The determination of red cell ferritin, based on a commercially available basic ferritin assay, can have clinical application. It can be used for evaluating the adequacy of the iron supply to the erythroid marrow, particularly in patients with increased red cell turnover. Moreover, it may be useful in evaluating the body iron status in patients with hemochromatosis and liver disease.
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PMID:Biologic and clinical significance of red cell ferritin. 662 42

Pulse-chase analysis of newt (Triturus cristatus) erythroblasts has shown that ferritin is not a primary source of iron for heme synthesis. During chase incubation with and without non-radioactive plasma iron in the medium, no transfer of 59Fe from ferritin to hemoglobin was detected although the integrity of heme synthesis was maintained. In puromycin-inhibited cells where iron uptake was drastically curtailed, heme synthesis continued to occur, though at reduced levels; incorporation of 59Fe from the plasma appeared initially in heme and hemoglobin without any prior labelling of ferritin. These results indicate that ferritin is neither an obligatory iron intermediate in heme synthesis nor a cytosolic transport molecule involved in mobilization of iron from the transferrin-receptor complex. The most likely role for erythroid ferritin is storage of excess iron.
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PMID:Ferritin is not a required intermediate for iron utilization in heme synthesis. 669 47

The relationship between the level of erythropoiesis and iron balance was evaluated in 13 subjects with idiopathic refractory anemias. Serum ferritin levels and bone marrow iron stores were increased only in those patients with ring sideroblasts, erythroid hyperplasia and ineffective erythropoiesis. The magnitude of the increase correlated with the duration of anemia and the degree of increase in the erythron iron turnover. Ferritin levels were not related to the severity of the anemia, indicating that increased iron stores did not represent a shift of iron from the erythron or an absorption response to anemia per se. It does suggest that the level of erythroid proliferation directly affects gastrointestinal iron absorption, which in time leads to iron overload.
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PMID:Serum ferritin in refractory anemias. 679 92

Sequential lysis of human bone marrow cells with a monoclonal antibody directed against myeloid cells (TG1) and a rabbit antiserum raised against peripheral blood mononuclear cells gave preparations in which 78-97% of the nucleated cells were erythroid, with a 24-77% recovery. Viability was high, morphology was good and the cells were able to divide and differentiate in culture. No metabolic experiments were carried out but the ferritin content of the erythroblasts was measured in four experiments and found to be about 200-2000 times higher than that found in normal erythrocytes. The H/S ratio was high in both erythroblasts and erythrocytes. Fractionation on the basis of density of two erythroblast preparations, one from a patient with sideroblastic anaemia and one from a patient with megaloblastic anaemia, showed that the most immature erythroblasts contained the highest content of ferritin and that this fell with maturation. The H/S ratio stayed the same or fell with maturation. It was concluded that this method would be valuable for the study of the role of erythroblast ferritin in normal and pathological situations.
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PMID:Enrichment of erythroblasts from human bone marrow using complement-mediated lysis: measurement of ferritin. 682 52

The avidin-biotin complex was used for the selective ultrastructural labeling of terminal cell surface galactosyl residues. Rabbit bone marrow cells were treated with the enzyme galactose oxidase in the presence of biotin hydrazide. Subsequent treatment with ferritin-avidin conjugates enabled the electron microscopic visualization of terminal membrane-based galactose and/or N-acetylgalactosamine on these cells. All stages of erythroid development were characterized by high levels of exposed cell surface galactose, whereas all leukoid cells in the same preparations were virtually unlabeled by the above method. Modulations in the distribution of these surface determinants during differentiation and maturation of rabbit erythroid cells were found to concur in inverse fashion with respect to that of terminal sialic acids. Neuraminidase treatment, before the above labeling procedure, resulted in the exposure of additional galactosyl residues on the surface of all bone marrow cell types. The results indicate that a galactose-bearing glycoconjugate(s) may comprise an erythroid-specific membrane constituent of rabbit bone marrow cells. The high density of galactose on the surface of even the earliest erythroid precursors may eventually enable the identification and isolation of a stem cell, which already contains the erythroid-specific galactoconjugate(s). The results suggest that variations in the spectrum of cell surface carbohydrates may serve as recognition signals in the complex set of intercellular interactions which occur during the development and maturation of the erythrocyte. The occurrence of similar but species-specific variations in the complement of surface heterosaccharides during erythroid development of humans and other mammals supports this contention.
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PMID:Cell-type-related segregation of surface galactosyl-containing components at an early developmental stage in hemopoietic bone marrow cells in the rabbit. 682 46

Red cell ferritin was measured in normal subjects and patients with iron deficiency and iron overload by means of radioimmunoassays with antibodies to liver (basic) and heart (acidic) ferritins. In most of the subjects examined, red cells were found to contain greater amounts of heart-type than liver-type ferritin. The basic ferritin content reflected the abnormal body iron status both in iron deficiency and iron overload while the acidic ferritin content was less closely related to the iron status. The two immunologically different red-cell ferritins probably represent distinct ferritin molecules and may have different metabolic functions within haem-synthesizing erythroid cells.
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PMID:Ferritin in the red cells of normal subjects and patients with iron deficiency and iron overload. 683 Jul 6

The relationship between body iron status, degree of anaemia, erythroid expansion, age and sex has been studied in eight patients with congenital dyserythropoietic anaemia (CDA) and two patients with congenital sideroblastic anaemia, who had received no or very few blood transfusions and no medicinal iron during the course of their illness. All patients had increased iron stores. Iron load was mild in three women in the reproductive age and severe in two men, in middle age, who had evidence of parenchymal organ dysfunction. Iron loading, as judged by the plasma ferritin concentration, was independent of the degree of anaemia while it was closely related to the patient's age and the degree of increase in the total erythropoietic activity. It is concluded that patients with CDA or congenital sideroblastic anaemia are at high risk of developing haemochromatosis in middle age. Prophylactic phlebotomy or iron chelation therapy should be considered for such patients.
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PMID:Iron loading in congenital dyserythropoietic anaemias and congenital sideroblastic anaemias. 687 Nov 11

The regulation of ferritin synthesis by iron was examined in the reticulocytes of bullfrog tadpoles where the induction was 40- to 50-fold, increasing from 0.17 +/- 0.05% of total protein synthesis ([3H]leucine incorporation in cell suspension) to 7.4 +/- 1.6% following intraperitoneal injection of ferric ammonium citrate. No significant difference was observed between the levels of ferritin mRNA in control or iron-induced cells, determined by translation of isolated mRNA in a wheat germ system, demonstrating that ferritin induction by iron occurs by a post-transcriptional mechanism. Total protein synthesis in the wheat germ system was half-saturating at 10 micrograms of mRNA/ml whereas ferritin synthesis increased linearly up to 40 micrograms of mRNA/ml, demonstrating that the ferritin mRNA is translated with high efficiency relative to the total proteins synthesized. Studies with the cap analogue 7-methylguanosine-5'-monophosphate, suggest that cap binding is not directly involved in the high translational efficiency of the ferritin mRNA in the wheat germ system. The results indicate that iron-modulated changes in the availability of ferritin mRNA for translation, coupled with the high translational efficiency of the ferritin message, can account for the induction of ferritin synthesis by iron in embryonic erythroid cells.
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PMID:Translational control of ferritin synthesis by iron in embryonic reticulocytes of the bullfrog. 698 98

In avian erythroid cells the erythrocyte-specific histone H5 is involved, like H1, in the packing of nucleosomes in the 25-nm chromatin fibers. In this study the distribution of histone H5 along the polynucleosomal chains was visualized by immunoelectron microscopy. Trinucleosomes from chicken erythrocytes and liver were used in order to test the specificity of the reaction with purified rabbit anti-H5 antibodies at various ionic strengths (5-80 mM). Long-chain chromatin was then reacted with anti-H5 antibodies and with sorted monomeric ferritin conjugate under chosen conditions. The antigenic determinants of histone H5 in the 25-nm fiber of long-chain chromatin (at 80 mM NaCl) are as accessible to the specific antibodies as in trinucleosomes. When the immunocomplexes were examined by electron microscopy in a low-ionic-strength buffer, permitting maximum extension of the chromatin structure on the grid, clusters of compacted nucleosomes were seen, separated by short regions of relaxed nucleosomes. Single nucleosomes enlarged by the antibodies are sometimes visible in the extended domains. We conclude that histone H5 is located primarily on series of adjacent nucleosomes but it can also be found on single nucleosomes located in the H1-enriched extended domains.
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PMID:Localization of histone H5 in the subunit organization of chromatin using immunoelectron microscopy. 714 Jul 53

Vesicles attached to the cell membrane of enucleating normoblasts and reticulocytes are considered indicative of the segregation of plasmalemmal components. The vesicles are obviously free from haemoglobin. They bind cationized ferritin and autologous immunoglobulin G. This segregation of plasmalemmal constituents is suggested to be one line of erythroid cell maturation.
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PMID:Lipid segregation from the maturing erythroid cell membrane. 738 63


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