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

An immunoperoxidase staining technique was used for detecting three major iron-binding proteins (transferrin, ferritin, and lactoferrin) in routine histological paraffin sections of human tissue. Transferrin was found mainly in hepatocytes, a variety of epithelial and myoepithelial cells, renal tubular cells, and histiocytes. Ferritin was most readily found in histiocytes and liver cells, with weaker reactions seen in epithelial cells. Lactoferrin was found in lactating breast tissue, bronchial glands, polymorphs, and gastric and duodenal epithelial cells. The technique is potentially valuable for investigating abnormal iron states.
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PMID:Distribution of transferrin, ferritin, and lactoferrin in human tissues. 34 12

In order to follow the dynamics in the reaction of iron kinetic variables to acute infection, 8 renal transplantation patients were followed with test samples every second or third day for about two months. It was found that they just as previously shown in otherwise healthy subjects, responded to acute infection with a rise in serum ferritin levels, sometimes to very high values. In most cases the ferritin elevation started within two days after the onset of fever. The peak was reached within a week, except when very high values were obtained. The fall in serum ferritin after recovery from infection was much faster than in previously investigated groups of patients: the plasma half disappearance time for ferritin in one case was but 1.5 days. Transferrin did not change in response to infection. The expected fall in serum iron during infection was often absent and sometimes obscured by unexpected, sharp peaks in serum iron, which bore a temporal relationship to episodes of transplant rejection in 7 of 12 cases.
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PMID:Serum ferritin during infection. A longitudinal study in renal transplant patients. 38 53

A Triton X-100 solubilized macromolecular complex of transferrin and a membrane constituent can be isolated by gel chromatography from rabbit reticulocytes previously incubated with 125I-labeled transferrin. The apparent molecular weight of this complex is close to that of ferritin, or about 445 000. On sodium dodecyl sulfate gel electrophoresis the complex displays two glycoprotein subunits, of molecular weights 176 000 and 95 000 in addition to transferrin. A transferrin-binding fraction with a molecular weight near 400 000, containing these subunits, can also be identified in membranes of nonincubated reticulocytes. The corresponding membrane fraction from mature erythrocytes, which have lost transferrin-binding activity, displays both protein subunits, but the 176 000 molecular weight component fails to give a PAS stain for carbohydrate. Treatment of reticulocytes with Pronase, which destroys the ability of the cells to form specific complexes with transferrin, degrades both components. We believe these results are consistent with the hypothesis that the primary transferrin receptor of the rabbit reticulocyte is a glycoprotein of molecular weight in the range 350 000-400 000, comprised of a combination of two subunits with molecular weights 176 000 and 95 000, respectively. Transferrin-binding activity appears to depend on the carbohydrate moiety of the 176 000 subunit.
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PMID:Transferrin receptor of the rabbit reticulocyte. 84 17

This paper reviews and reports the results of experiments on the mechanism by which iron is delivered from extracellular transferrin to reticulocyte mitochondria in which haem is synthesized. It is suggested that transferrin donates the iron directly to mitochondria. Transferrin seems to be bound to mitochondria during the process of iron release. When the release of iron from transferrin is blocked by haem, the iron-transferrin complex remains bound to mitochondria so that the total amount of transferrin molecules associated with mitochondria increases in haem-treated reticulocytes. This also leads to an increase in the number of transferrin molecules in the cytosol. In haem-deficient reticulocytes, the rate of dissociation of iron from transferrin is accelerated and the uptake of iron by mitochondria is increased. When the synthesis of haem is inhibited, the non-haem iron in the cytosol (i.e. mainly low-molecular-weight and ferritin iron) comes from mitochondria. Greater amounts of non-haem iron can also be induced in reticulocytes incubated with highly saturated transferrin but, in this case, iron does not seem to be accumulated in mitochondria. These results represent an experimental basis for the elucidation of the excessive non-haem iron accumulation in erythroid cells observed in various clinical conditions.
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PMID:Control of iron delivery to haemoglobin in erythroid cells. 105 29

The anatomical and cellular distribution of non-haem iron, ferritin, transferrin, and the transferrin receptor have been studied in postmortem human brain and these studies, together with data on the uptake and transport of labeled iron, by the rat brain, have been used to elucidate the role of iron and other metal ions in certain neurological disorders. High levels of non-haem iron, mainly in the form of ferritin, are found in the extrapyramidal system, associated predominantly with glial cells. In contrast to non-haem iron, the density of transferrin receptors is highest in cortical and brainstem structures and appears to relate to the iron requirement of neurones for mitochondrial respiratory activity. Transferrin is synthesized within the brain by oligodendrocytes and the choroid plexus, and is present in neurones, consistent with receptor mediated uptake. The uptake of iron into the brain appears to be by a two-stage process involving initial deposition of iron in the brain capillary endothelium by serum transferrin, and subsequent transfer of iron to brain-derived transferrin and transport within the brain to sites with a high transferrin receptor density. A second, as yet unidentified mechanism, may be involved in the transfer of iron from neurones possessing transferrin receptors to sites of storage in glial cells in the extrapyramidal system. The distribution of iron and the transferrin receptor may be of relevance to iron-induced free radical formation and selective neuronal vulnerability in neurodegenerative disorders.
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PMID:Brain iron homeostasis. 143 85

In order to further study the relation between transferrin receptor and erythropoiesis we examined serum receptor levels in megaloblastic anemia, which is the classic example of ineffective erythropoiesis. We studied 33 patients with unequivocal cobalamin deficiency, only 22 of whom were anemic. High serum transferrin receptor levels were found in 12 patients, all of whom were anemic and had high lactate dehydrogenase (LDH) levels; in contrast, only 10 of the 21 patients with normal receptor levels were anemic. Receptor correlated most strongly with LDH (r = 0.573, p < 0.001) and, inversely, with hemoglobin values (r = -0.560, p < 0.001); it also correlated with ferritin and total bilirubin levels, but not with cobalamin, MCV or erythropoietin. No association was found with the hemolytic component of megaloblastic anemia, represented indirectly by haptoglobin levels. Changes induced by cobalamin therapy were also examined in 13 patients. Transferrin receptors rose in all 6 patients who initially had high levels and in 2 of 3 patients who had borderline levels, but not in the 4 patients with initially normal levels. The receptor levels began to rise within 1-3 days, peaked at about 2 weeks and returned to normal at about the 5th wk. The findings indicate that serum transferrin receptor levels reflect the severity of the megaloblastic anemia. The elevated receptor levels rise further with cobalamin therapy, however, as effective erythropoiesis replaces ineffective erythropoiesis, and these persist until the increased erythropoiesis returns to normal.
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PMID:Serum transferrin receptor in the megaloblastic anemia of cobalamin deficiency. 147 86

Campylobacter jejuni strains were tested for their ability to acquire iron from various iron sources present in humans. Hemin, hemoglobin, hemin-hemopexin, and hemoglobin-haptoglobin stimulated the growth of C. jejuni strains in low-iron medium. Transferrin, lactoferrin, and ferritin were unable to provide iron to the strains tested. Derivatives of the naturally transformable C. jejuni strain 81-176 were isolated on the basis of their inability to use hemin as an iron source. These mutants were also unable to use hemoglobin, hemin-hemopexin, or hemoglobin-haptoglobin as iron sources. Some mutants lacked a 71,000-Da iron-regulated outer membrane protein, while others appeared to retain all of their outer membrane proteins. Growth curves and a recombination experiment that exploited natural transformation were used to further characterize the mutants. A hemolytic activity was shown to be produced by several C. jejuni strains, but it did not appear to be iron regulated.
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PMID:Iron acquisition and hemolysin production by Campylobacter jejuni. 150 Jan 94

Despite recognition that iron is important for normal neurological function, the proteins involved in maintaining iron homeostasis within the brain have until recently received little attention. In the past few years, studies aimed at determining both general and cellular control of iron in the brain have increased. Histological studies indicate that maintenance of iron homeostasis in the brain is the responsibility of neuroglia and possibly the choroid plexus. Transferrin, the iron transport protein, has been found predominantly in oligodendrocytes in the brain and in myelinating Schwann cells in the peripheral nervous system. The messenger RNA for transferrin is located in the brain in oligodendrocytes and the choroid plexus. Most of the transferrin protein and transcript expression in the brain is dependent on the presence of a mature population of oligodendrocytes. Transferrin is also involved in the transport of iron across the blood-brain barrier via transferrin receptors on brain capillary endothelial cells. The transferrin receptor is also present on cells within the brain. Ferritin, the iron storage protein, and iron are found in the brain in oligodendrocytes and microglia. Additional cells in which iron and ferritin are found are tanycytes, which are associated with the third ventricle. This latter observation raises interesting possibilities regarding the transport of iron from cerebrospinal fluid into the brain. The high iron requirement of the brain coupled with the high susceptibility of the brain to iron-generated peroxidative damage requires stringent regulation of the availability of iron. Consequently, the iron regulatory proteins are central to understanding mechanisms controlling iron-dependent activity at the cellular level, as well as protection of the brain from oxidative damage. The behavior of brain iron regulatory proteins will be a significant factor in future studies of the neurological diseases resulting from brain iron imbalance. We review the contributions of our laboratory to this field over the past 6 years, discuss current projects, and suggest future directions for study.
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PMID:Iron regulation in the brain: histochemical, biochemical, and molecular considerations. 151 Mar 81

The effect of different forms of iron and iron-binding proteins on the proliferative response of human lymphocytes to phytohaemagglutinin (PHA) has been studied. Transferrin enhanced proliferation, the effect being proportional to the degree of iron saturation up to 100%, but decreased if additional iron was present. The lipophilic complex ferric pyridoxal isonicotinoyl hydrazone (FePIH) also enhanced proliferation, but the hydrophilic complex ferric nitrilotriacetate (FeNTA) was inhibitory. Fe-lactoferrin could not substitute for Fe-transferrin, although iron-free (apo) lactoferrin abrogated the inhibitory effect seen when iron levels exceed the binding capacity of transferrin. Lymphocyte ferritin levels increased 4-fold as the iron saturation of transferrin increased from 0 to 90% but no further increase was seen at higher iron levels, suggesting that lymphocytes are poorly equipped to detoxify excess iron through stimulation of ferritin synthesis. The effect of iron on the CD4:CD8 ratio after 72 h culture with PHA was also examined. The ratio was approximately 2:1 for cells cultured with transferrin at iron saturations between 0 and 75%, with FePIH, or without either, but decreased to 1.1:1 when cells were cultured in the presence of FeNTA, regardless of whether or not saturated Fe-transferrin was present. These results show that iron can affect lymphocyte proliferation and subset ratios in different ways according to the form and amount present, and may help to explain some of the immunological disturbances associated with iron overload.
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PMID:Effect of transferrin, lactoferrin and chelated iron on human T-lymphocytes. 155 Jul 82

Serum trace element concentrations, parameters of iron metabolism and serum protein concentrations were investigated in thirteen adult recipients of bone-marrow transplants receiving total parenteral nutrition. Six of the patients died during the four weeks follow-up. Serum zinc concentrations were initially low but increased during the treatment. They also tended to be lower in dying patients than in survivors. Concentrations of serum copper and selenium remained unaltered. Serum iron started to increase during the preconditioning and remained raised for three weeks. No significant changes occurred in serum transferrin levels. Transferrin saturation increased during the preconditioning and started to return to normal after day +14. Serum ferritin was greatly raised from the start and increased further during the procedure. Routine trace element substitution seemed to be sufficient during total parenteral nutrition with the possible exception of zinc. A return to normal transferrin saturation after day +14 may be an early favourable sign that the graft is taking and hematopoietic recovery commencing.
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PMID:Serum trace element concentrations and iron metabolism in allogeneic bone marrow transplant recipients. 157 60


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