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

Estrogen causes the cytoplasmic destabilization of albumin and gamma-fibrinogen mRNA in Xenopus laevis liver. The purpose of the present study was to determine whether mRNA destabilization is a generalized phenomenon in response to estrogen, or whether this process is restricted to a particular class of mRNAs. To address this, we have expanded our bank of serum protein-coding cDNA clones to include transferrin, the second protein of inter-alpha-trypsin inhibitor and clone 12B, for which there is no mammalian homolog. Together with albumin and gamma-fibrinogen, these represent more than 85% of the mRNAs encoding liver secreted proteins. Estrogen administration to male Xenopus or to liver explant cultures causes the generalized disappearance of all of these mRNAs. In contrast, estrogen has no effect on actin, ferritin, or poly(A)-binding protein mRNA, all of which encode intracellular proteins. We have previously demonstrated that albumin mRNA is degraded in both messenger ribonucleoprotein and polysome fractions. Sucrose gradient analysis demonstrates the same pattern for degradation of all other serum protein-coding mRNAs. Estrogen has no effect on the amounts or gradient distribution of actin, ferritin, or poly(A)-binding protein mRNA. We conclude that regulated destabilization of mRNAs encoding secreted proteins is a generalized phenomenon in response to estrogen stimulation of Xenopus liver.
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PMID:Coordinate estrogen-regulated instability of serum protein-coding messenger RNAs in Xenopus laevis. 192 78

Protein-carbohydrate recognition has been found to play an important role in phagocytosis. Labelled (neo)glycoproteins were employed to comparatively analyze the histochemical pattern and ultrastructural localization of endogenous carbohydrate-binding proteins (lectins) of mononuclear macrophages and multinucleate giant cells involved in the granulomatous foreign body reaction. Sugar receptors having an affinity to simple alpha- and beta-galactoside-structures, to alpha-mannose residues, to N-acetylglucosamine, to N-acetylgalactosamine and to glucuronic acid, respectively, were detected in both cell types. However, alpha-fucoside- and beta-xyloside-specific receptors were present only in the mononuclear macrophages. Pronounced differences were seen with labelled, suitably modified glycoproteins, exposing different complex sugar parts with common beta-galactoside-termini. Among the population of multinucleate giant cells, a positive histochemical reaction was observed with mannose-6-phosphate-, galactose-6-phosphate- and glucuronic acid-(BSA-biotin), respectively, only in giant cells in which fusing mononuclear cells were recognizable. This transient expression indicates changes within the profile of endogenous sugar receptors in the stages from fusion to establishment of giant cells. Aside from the diffuse intracytoplasmic distribution of carbohydrate-binding proteins, a prominent accumulation of various types of glycosylated ferritin, used as a marker for electron microscopic evaluation, was ultrastructurally found in membranous subcellular structures and vesicles. This study is a basis for further investigation of the potential involvement of various sugar receptors in the process of macrophage fusion, resulting in multinucleate giant cells of foreign body type, and the process of phagocytosis.
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PMID:Are glycoconjugates and their endogenous receptors involved in the fusion of mononuclear macrophages resulting in multinucleate giant cells? Histochemical and electron microscopic determination of endogenous sugar-binding proteins (lectins) in mononuclear macrophages and multinucleate giant cells appearing in granulomatous foreign body reaction. 254 62

1. The iron contents, gel migration rates and isoelectric-focusing patterns of normal liver and hepatocellular carcinoma ferritins from the same patients were compared. 2. Sucrose-density-gradient centrifugation showed that the number of iron atoms per ferritin molecule was decreased to approximately half in carcinoma tissue when compared with normal liver. 3. On electrophoresis, hepatocellular carcinoma ferritin migrates faster and is therefore more negatively charged than normal liver ferritin, thus refuting the general view that the more negatively charged a ferritin molecule the greater its iron content. 4. Comparison of tumour and normal liver ferritin subunit compositions on acid/urea/polyacrylamide gels showed hepatocellular carcinoma ferritin to contain an additional, more negatively charged, subunit to normal liver ferritin. 5. Isoelectric focusing showed that hepatocellular carcinoma tissue contains isoferritins with isoelectric points intermediate between the ranges of normal liver and normal heart isoferritins.
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PMID:A biochemical comparison of normal human liver and hepatocellular carcinoma ferritins. 624 28

Plasma membrane vesicles of rat myometrium were prepared in media containing 240 mM sucrose. The vesicles were exposed to isotonic, hypertonic, and hypotonic sucrose concentrations, fixed, sectioned, and studied using the electron microscope. The vesicles fixed in isotonic media were circular in appearance. Vesicles fixed in hypertonic media were distorted and showed a reduced volume to surface ratio consistent with the hypothesis that greater than 80% of the vesicles were osmotically active to sucrose. Cationized ferritin binding studies and Ca binding and release studies were also consistent with this finding. Exposure to hypotonic media also yielded membranes with distorted profiles indicating that they had been ruptured. [3H]Sucrose trapping experiments revealed that the vesicles had an internal volume of 1.20-1.44 mL/g protein. Hypotonic shock treatment reduced this intravesicular volume to 0.20-0.28 mL/g protein. The hypotonic shock treatment also led to enhanced galactose oxidase catalyzed Na3B3H4 labelling of the membranes and to increased K+-activated ouabain-sensitive p-nitrophenyl phosphatase activity. The enhancement was the same (55 +/- 10%) in the various membrane preparations for both the parameters. The data are interpreted to conclude that the rat myometrium plasma membrane vesicles consisted of 20% broken vesicles and equal proportions of intact vesicles of inside-out and rightside-out orientations.
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PMID:Smooth muscle membrane vesicle orientation: a study on intactness and sidedness of rat myometrium plasma membrane vesicles. 625 66

Previous studies have suggested that sugars enhance iron bioavailability, possibly through either chelation or altering the oxidation state of the metal, however, results have been inconclusive. Sugar intake in the last 20 years has increased dramatically, and iron status disorders are significant public health problems worldwide; therefore understanding the nutritional implications of iron-sugar interactions is particularly relevant. In this study we measured the effects of sugars on non-heme iron bioavailability in human intestinal Caco-2 cells and HepG2 hepatoma cells using ferritin formation as a surrogate marker for iron uptake. The effect of sugars on iron oxidation state was examined by measuring ferrous iron formation in different sugar-iron solutions with a ferrozine-based assay. Fructose significantly increased iron-induced ferritin formation in both Caco-2 and HepG2 cells. In addition, high-fructose corn syrup (HFCS-55) increased Caco-2 cell iron-induced ferritin; these effects were negated by the addition of either tannic acid or phytic acid. Fructose combined with FeCl3 increased ferrozine-chelatable ferrous iron levels by approximately 300%. In conclusion, fructose increases iron bioavailability in human intestinal Caco-2 and HepG2 cells. Given the large amount of simple and rapidly digestible sugars in the modern diet their effects on iron bioavailability may have important patho-physiological consequences. Further studies are warranted to characterize these interactions.
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PMID:Sugars increase non-heme iron bioavailability in human epithelial intestinal and liver cells. 2434 76

Different carbon sources lead to differential acarbose production in Actinoplanes. To uncover the underlying differentiation in the context of genes and pathways, we performed transcriptome sequencing of Actinoplanes utahensis ZJB-03852 grown on different saccharides, such as glucose, maltose, or the saccharide complex consisting of glucose plus maltose. The differentially expressed genes were classified into GO (gene ontology) terms and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways for functional annotations. Key enriched modules were uncovered. Our data revealed that both maltose and its complex with glucose gave improved acarbose titer. Sugar transportation, cytochrome oxidase, protein synthesis and amino acid metabolism modules were enriched under the saccharide complex condition, while ferritin metabolism gene expressions were enriched in the glucose medium. Our results provided the foundation for uncovering the mechanism of carbon source on acarbose production in A. utahensis.
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PMID:Transcriptome analysis of Actinoplanes utahensis reveals molecular signature of saccharide impact on acarbose biosynthesis. 3308 68