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)

Normal young pigs were injected intravenously with azo dye Evans blue, which is preferentially and consistently taken up by focal areas in the aorta known to be areas of enhanced permeability. Ferritin was intravenously injected into these animals, and its uptake was quantitated at the electron microscope level at 1, 5 and 15 min after administration. The number of vesicles, large inclusions or vacuoles, and junctions, both labelled and unlabelled, were counted in areas of normal and enhanced permeability. The results have revealed that the number of ferritin grains per vesicle is the same in both areas. However, the percentage of vesicles containing ferritin is significantly higher in areas of enhanced permeability.
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PMID:Structural correlates of arterial endothelial permeability in the Evans blue model. 20 Sep 55

Prostaglandin F2 alpha (PGF2 alpha) binds specifically to a partially purified membrane preparation from rat corpora lutea. The high affinity, low capacity binding component asa a Kd = 4.7 nM and has a capacity of 0.38 pmol/mg protein. Binding kinetics were temperature-dependent with an association rate constant of 2.5 x 10(5) 1/mol-sec and a dissociation rate constant of 4.3 x 10(-4) sec-1 at 22 degrees C. Little competition for binding was shown by other prostaglandins and prostaglandin metabolites; the PGF2 alpha analogue ICI 81008 (16-m-trifluoromethylphenyl-prostaglandin F2 alpha) showed a binding affinity similar to that of PGF2 alpha. The specific binding of PGF2 alpha to luteal cell membranes was confirmed by electron microscopy using a ferritin--PGF2 alpha conjugate. Ferritin--PGF2 alpha was found predominantly on luteal cell surfaces; little binding occurred on other types of cells present. These data demonstrate specific binding of PGF2 alha to rat luteal membranes. It is suggested that the luteolytic action of PGF2 alpha in the rat may be receptor-mediated.
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PMID:Specific binding of prostaglandin F2 alpha to membranes of rat corpora lutea. 22 Dec 85

Ferritin was dissociated into subunits by various denaturants and the subunits were examined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Human, horse, rat, and rabbit ferritins all exhibited characteristic patterns of heterogeneity; components with molecular weights of about 19,000, 11,000, and 8,000 were invariably found in these preparations. This result contradicts earlier reports that ferritin consists of 24 identical subunits. These polypeptides were isolated, purified in the presence of low concentrations of detergent, and characterized. Evidence based on amino acid compositions, NH2-terminal analysis and investigation of detergent-induced breakdown products, indicated that the 19,000 molecular weight component is a composite of the 8,000 and 11,000 molecular weight chains. Circular dichroism studies showed that the 19,000 molecular weight polypeptide retained appreciable amounts of ordered secondary structure whereas the two lower molecular weight peptides were unfolded to a much greater extent. If the 8,000 and 11,000 molecular weight polypeptides were recombined in equimolar amounts and the denaturant was completely removed, a substance with electrophoretic mobility and morphological appearance of native apoferritin was obtained.
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PMID:Characterization of the different polypeptide components and analysis of subunit assembly in ferritin. 23 40

Ferritin was purified from normal, fetal, and malignant liver tissue. Ferritin purified from hepatoma tissue migrated slightly faster than normal human liver ferritin in polyacrylamide gel electrophoresis. Hepatoma and fetal liver ferritin contained an acidic components in gel and liquid isoelectric focusing not found in normal liver ferritin. We have called it a carcinofetal isoferritin. The subunit compositions of ferritins purified from human liver cell carcinoma and normal liver were then compared. Both ferritin consisted of a subunit species with an identical molecular weight of approximately 18,500. A single subunit of similar molecular weight was also demonstrable after dissociation of 8 M urea and by gel filtration in urea. Two subunits were demonstrable in normal liver ferritin by means of acrylamide electrophoresis in 8 M urea in acid pH. The same two subunits were also demonstrable in ferritin isolated from human liver cell carcinoma. However, a third subunit, intermediate in charge between the two normal liver subunits, was demonstrable in different amounts in ferritins from two hepatomas. Ferritins from normal and malignant livers were immunologically indistinguishable. The tumor-specific acidic isoferritin was isolated and antisera were prepared. The isolated acidic isoferritin was found to be immunologically identical to normal liver isoferritins. It is concluded that the multiple isoferritins of the human liver ferritin consist of two subunits, which are identical in molecular weight but which differ in net charge. Ferritin, isolated from two human liver carcinoma tissues, was composed of the same two subunits and a third unique subunit. Different amounts of these subunits may account for the several normal isoferritins and a unique tumor-specific acid isoferritin found in hepatoma.
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PMID:Characterization and subunit analysis of ferritin isolated from normal and malignant human liver. 23 22

Leucocytes containing a high proportion of blast cells were obtained from 11 patients with acute myeloid leukaemia, and leucocytes were also obtained from 2 normal subjects. Ferritin was partially purified from leucocyte extracts and subjected to anion-exchange chromatography and isoelectric focusing. The Fe content of leucocyte ferritin was low, and in all but one case the preparations contained isoferritins corresponding to those found in normal tissues or serum. Only some of the preparations contained the relatively acidic isoferritins which have been described as "carcinofoetal", but which are also present in normal heart and kidney. Ferritin from one patient contained isoferritins of lower isoelectric point than heart ferritin. These results show that there does not appear to be any specific isoelectric focusing pattern for leukaemic cells, and that assays for acidic isoferritins are unlikely to be of use in the diagnosis of leukaemia and in monitoring treatment. However, the very acidic protein found in one preparation suggests that the search for abnormal subunits of ferritin may be fruitful in acute leukaemia.
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PMID:Isoferritins in acute leukaemia. 26 5

Nicotinic acetylcholine receptor was localized in a receptor-rich membrane preparation from the electric organ of Torpedo californica by applying an immunoferritin technique. The membrane preparation was incubated with (Fab')2 fragments derived from specific rabbit antibodies against the purified acetylcholine receptor and subsequently with ferritin-conjugated goat antiserum to rabbit immunoglobulin. More than 50% of the vesicles were found to be labeled with ferritin while the rest remained unlabeled. Ferritin labeling on both sides of the membrane was evident in open membrane vesicles, whereas in closed vescles the labeling was confined to the outer surface due to the inability of the tracer to penetrate the membrane. These data suggest that antigenic sites of the receptor molecule are exposed on both sides of the excitable membrane, and that acetylcholine receptor may be a transmembrane protein.
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PMID:Localization of acetylcholine receptor in excitable membrane from the electric organ of Torpedo: Evidence for exposure of receptor antigenic sites on both sides of the membrane. 27 86

The circulating red blood cells formed in bullfrog larvae, chicken embryos, and mouse embryos contain large amounts of ferritin and storage iron in excess of the need for hemoglobin. In contrast, the circulating red cells of adult animals contain little ferritin. Ferritin synthesis and iron storage are coordinated with differentiation and hemoglobin synthesis in the red cells of adults. In order to test the hypothesis that ferritin synthesis could be controlled independently of hemoglobin synthesis and differentiation in the red cells formed early in life, bullfrog larvae were injected with iron to determine if ferritin synthesis was increased in the circulating red cells. Within 17 h after the injection of iron, the synthesis of ferritin, assayed as the incorporation of [14C]leucine by cell suspensions prepared from circulating red cells, was increased from 2.9 to 10.2% of the total protein, and the specific activity of the ferritin synthesized increased from 1100 to 3000 cpm/A280. There was no change in the hematocrit of the animals nor in the specific activity of hemoglobin synthesized by suspensions of red cells (average, 720 cpm/A280). The results suggest that in mature, larval red cells, ferritin synthesis can be controlled by changes in the extracellular environment. The results also indicate that ferritin synthesis can be controlled independently of hemoglobin synthesis with which it is coordinated during erythroid differentiation in adult animals.
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PMID:The induction of ferritin synthesis in circulating larval red blood cells. 30 18

Filtration studies suggest similar size pores in the glomerular filters of mammals and amphibians. However, the glomerular wall in the bullfrog exhibits several structural features not found in mammals. The subendothelial space of the basement membrane is often greatly enlarged and infiltrated by cellular elements. The lamina densa of the basement membrane shows extensive variation in thickness and packing of its filaments. On the other hand, the epithelial slits in the bullfrog are closed by a slit diaphragm which appears similar in size and structure to the slit diaphragm in mammals. Horse spleen ferritin, a protein with a hydrodynamic radius of 61 A, was used as an ultrastructural tracer to determine whether the highly variable structure of the basement membrane renders this layer more permeable than its mammalian counterpart. Within 10 min after intravenous injection, ferritin was found throughout the basement membrane and often in clusters within the subepithelial layer adjacent to the slit diaphragm. Virtually no ferritin was found within the urinary space, podocytes, or cells of the proximal tubule. Ferritin distribution was the same in both superficial glomeruli and more deeply lying glomeruli regardless of the method of fixation. These results indicate that in the bullfrog the slit diaphragm is a principal filtration barrier to ferritin and thus to smaller plasma proteins.
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PMID:Glomerular permeability in the bullfrog Rana catesbeiana. 30 86

Localization of carbohydrate components in retinal photoreceptor cells and membranes was studied. Frog and rat retinas were fixed with glutaraldehyde and embedded in glycol methacrylate or in a mixture of glycol methacrylate, glutaraldehyde and urea. Thin sections were incubated with ferritin-labeled concanavalin A (F-Con A) and stained with osmium vapors. Intensive binding was observed in both rod and cone outer segments. In the rod inner segment, differential binding of F-Con A was demonstrated. While numerous ferritin granules were observed in the myoid zone, only a few were seen in the ellipsoid zone, except for a local accumulation along the plasma membrane. In the rod outer segment, Con A binding sites were closely associated with the disk membranes. Ferritin granules were observed on both sides of the membranes. The relationship between the localization of Con A binding sites and the orientation of visual pigment molecules within the rod outer segments disk membranes was discussed.
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PMID:Visualization of intracellular concanavalin A binding sites in retinal photoreceptors. 30 92

Ferritin-conjugated specific antibodies have been used to localize beta-galactosidase and both the monomer and active dimer of alkaline phosphatase in frozen thin sections of cells of Escherichia coli O8 strain F515. The even distribution of the ferritin marker throughout cells that had been induced for beta-galactosidase synthesis, frozen, sectioned, and exposed to ferritin-anti-beta-galactosidase conjugate showed that this enzyme was present throughout the cytoplasm of these cells. Frozen thin sections of cells that had been derepressed for the synthesis of alkaline phosphatase were exposed to both ferritin-anti-alkaline phosphatase monomer and ferritin-anti-alkaline phosphatase dimer conjugates, and the ferritin markers showed a peripheral distribution of both the monomer and the dimer of this enzyme. This indicates that alkaline phosphatase is present only in the peripheral regions of the cell and argues against the existence of a cytoplasmic pool of inactive monomers of this enzyme. This peripheral location of both the monomers and dimers of alkaline phosphatase supports the developing concensus that this enzyme is, like other wall-associated enzymes, synthesized in association with the cytoplasmic membrane and vectorially transported to the periplasmic area, where it assumes its tertiary and quaternary structure and acquires its enzymatic activity.
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PMID:Immunocytological investigation of protein synthesis in Escherichia coli. 32 33


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