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)

Release of the lysosomal enzyme beta-glucuronidase from human neutrophils was induced by IgG or its Fc fragment, aggregated by immune precipitation or by coating on latex particles. Such release was inhibited when the cells were preincubated with free IgG or Fc fragments; F(ab')2 fragments were ineffective in both inducing and inhibiting beta-glucuronidase release. Neutrophils incubated with IgG or Fc fragments, when challenged with anti-IgG antibody, released lysosomal enzymes without the release of the cytoplasmic marker lactic dehydrogenase; These studies indicate that human neutrophils have surface receptors for the Fc portion of IgG. Neutrophils treated with IgG or its Fc fragment and subsequently with fluorescein- or ferritin-labeled anti-IgG showed binding of Fc or IgG to the cell membrane. Under suitable conditions, polar capping of labeled antibody was seen by fluorescence or electron microscopy. These studies suggest that the immunoglobulin receptors on neutrophils are redistributed when they are cross-linked with antibody. Fluidity of the membrane receptors appeared to be time and temperature dependent. Compounds such as 2-deoxyglucose, colchicine, and cyclic AMP, which inhibit the release of lysosomal enzymes, also inhibited the redistribution of the surface receptors. Cytochalasin B, an agent which increases the release, was found to increase the receptor redistribution; The relationship between the release of lysosomal enzymes and receptor mobility is discussed;
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PMID:Redistribution of immunoglobulin receptors on human neutrophils and its relationship to the release of lysosomal enzymes;. 18 51

The formation of irreversible complexes between carrier ampholyte components and proteins was investigated by gel filtration of mixtures of proteins and radioactively labelled ampholytes. Experiments were performed both with purified proteins (albumin, ferritin, beta-glucuronidase) and with a complex mixture of proteins (serum); in no case was binding of ampholytes to proteins detected. Thus the results argue against the occurrence in isoelectric focusing of proteins of artifacts due to such complex formation.
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PMID:Evidence against the occurrence of artifacts due to carrier ampholyte-protein binding during isoelectric focusing. 23 9

The vertebrate muscle spindle has been observed to be ionically and biochemically isolated from the surrounding muscle fibers by the spindle capsule. We have explored the possibility that the capsular cells are endocytically active and can transport both small molecules and macromolecules into the capsular space. Transcytosis (the endocytic transport of extracellular substances across a cell) through the capsule cell layer was examined with muscle spindles of snake, rat, and cat using fluorescent markers for fluorescence microscopy and horseradish peroxidase (HRP) and ferritin for electron microscopic examination. The fluorescent markers were actively taken up by capsule cells, making it easy to locate the spindle capsular region of spindles among extrafusal fibers by their strong fluorescence. Ferritin and HRP were used to identify the pathway of transcytosis by electron microscopy. These markers were found in endocytic vesicles of capsule cells, in the narrow space between capsule layers and in the capsular space, indicating that the marker was transferred to the capsular space by the pinocytic activity of capsule cells. Scattered cells in the capsule of cat muscle spindles appeared to take up fluorescein isothiocyanate (FITC)-coupled beta-glucuronidase by a receptor-mediated process. The uptake was sensitive to temperature and [Ca2+], and specifically inhibited by yeast mannan. By electron microscopy with dilute HRP (10 micrograms/ml) this specific uptake was by isolated cells in the interlamellar space. The functional significance of the above findings is discussed.
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PMID:Endocytosis and transcytosis by the capsule cell of vertebrate muscle spindles. 280 78

Blood enzymatic activities in gastric carcinoma depend on the release from carcinomatous tissues, surrounding non-neoplastic tissues, increased permeability and necrosis of carcinomatous tissues. However, those enzymatic activities did not parallel the extent and macroscopic appearance of the tumor. Various enzyme proteins and gastrointestinal hormones concerning gastric carcinoma and intestinal metaplasia including pepsin, LDH, AFP, beta-glucuronidase, rGTP, lysozyme, ferritin, sialic acid, polyamine, CEA, Ca 19-9, collage, gastrin, immunoglobulin are discussed in this paper. The variation of enzymes and proteins occurring in gastric carcinoma and intestinal metaplasia are well documented. Some of them would be a useful indicator of diagnosis and treatment as a tumor marker.
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PMID:[Various enzymatic activities in gastric carcinoma and intestinal metaplasia]. 309 81

A combined cytochemical and electron microscopical study has delineated a new type of an erythrocytic inclusion body. Enzyme cytochemically these inclusions are characterized by beta-glucuronidase as a marker enzyme. In part, the inclusions may contain acid phosphatase and ferritin. The inclusions develop in mature erythrocytes since beta-glucuronidase normally does not occur in erythroblasts and, in general, this type of inclusion body is not found in erythroblasts. Based upon our preliminary findings, the hypothesis is extended that beta-glucuronidase is taken up via receptor-mediated endocytosis into erythrocytes and is finally put into clustered cytolysosomal vaculoes, that account for the inclusion bodies as seen at light microscopy. Exogenous beta-glucuronidase might be contributed for by breakdown of cells (e.g. hepatocytes) producing this enzyme in considerable amounts numbers. This view is corroborated by the observation that most patients with beta-glucuronidase-positive inclusions suffered from various chronic disorders of the liver.
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PMID:Beta-glucuronidase-positive erythrocytic inclusion bodies--a hitherto unknown phenomenon. 398 12

1. beta-Glucuronidase (EC 3.2.1.31) was purified from rabbit liver by a procedure involving autolysis, (NH(4))(2)SO(4) fractionation, chromatography on DEAE-cellulose and hydroxyapatite, gel filtration, sedimentation in a sucrose gradient, and isoelectric focusing. 2. Electron microscopy revealed ferritin as the major contaminant in later stages of purification and also showed aggregates of enzyme molecules. Particular attention was paid to the removal of ferritin. 3. The purified enzyme was homogeneous in polyacrylamide-gel electrophoresis both in non-dissociating conditions and in the presence of sodium dodecyl sulphate, and in Ouchterlony gel diffusion and immunoelectrophoresis against polyspecific antisera. 4. Sedimentation in sucrose gradients gave a molecular weight of 300000, whereas gel filtration indicated 440000. 5. Subunits of 75000 molecular weight were observed in gel electrophoresis in the presence of sodium dodecyl sulphate and in gel filtration in the presence of urea. 6. The K(m) value for p-nitrophenyl beta-d-glucuronide was 0.6mm, and the enzyme was extremely sensitive to lactone inhibitors. It was also inhibited by Hg(2+) ions. 7. Multiple forms were observed in the pure enzyme by isoelectric focusing, with pI values of 4.5-5.8. Subunits showed similar heterogeneity. The origin of the multiple forms was investigated in detail, and the possibility of artifact generation largely excluded. Some of the forms of lowest pI disappeared after neuraminidase digestion. The nature of the residual heterogeneity remains to be elucidated.
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PMID:Rabbit beta-glucuronidase. Purification and properties, and the existence of multiple forms. 421 18

Two pathways have been implicated in the regulation of maize ferritin synthesis in response to iron. One of them involves the plant hormone abscisic acid (ABA) and controls the expression of ZmFer2 gene(s). Another pathway, ABA-independent, has been characterized in a de-rooted maize plantlet system and involves an oxidative step. The ZmFer1 maize ferritin gene is not regulated by ABA, and it is shown in this paper that the corresponding mRNA accumulates in de-rooted maize plantlets and BMS (Black Mexican Sweet) maize cell suspension cultures in response to iron via the oxidative pathway described previously. To investigate ZmFer1 gene regulation further, the BMS cell system has been used to develop a transient expression assay using a ZmFer1-beta-glucuronidase fusion. Both iron induction and antioxidant inhibition of ZmFer1 gene expression were observed in this system. Using Northern blot analysis and transient expression experiments, it was shown that both okadaic acid and calyculin A, two serine/ threonine phosphatase inhibitors, specifically inhibit ZmFer1 gene expression. These data indicate that an okadaic acid-sensitive protein phosphatase activity is involved in the regulation of the ZmFer1 ferritin gene in maize cells, and this activity is required for iron-induced expression of this gene.
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PMID:Inhibition of the iron-induced ZmFer1 maize ferritin gene expression by antioxidants and serine/threonine phosphatase inhibitors. 940 24

Four different ferritin genes have been identified in Arabidopsis thaliana, namely AtFer1, 2, 3 and 4. AtFer1, which strongly accumulates in leaves treated with excess iron, contains in its promoter an Iron- Dependent Regulatory Sequence (IDRS). The IDRS sequence is responsible for repression of AtFer1 transcription under conditions of low iron supply. Arabidopsis plants transformed with a 1,400-bp AtFer1 promoter, with either a wild-type or a mutated IDRS fused to the beta-glucuronidase (GUS) reporter gene, enabled us to analyze the activity of the AtFer1 promoter in different tissues as well as during age-dependent or dark-induced senescence. Our results show that IDRS mediates AtFer1 expression during dark-induced senescence while it does not affect AtFer1 expression during age-dependent senescence or in young seedlings. Photoinhibition promoted either by high light or chilling temperature, or wounding, does not activate the AtFer1 promoter. In contrast, AtFer2, AtFer3, AtFer4 transcript abundances are increased in response to photoinhibition and AtFer3 transcript abundance is increased upon wounding. Taken together, our results indicate that other cis-elements, different from the IDRS, regulate the territory-specific or developmental expression of AtFer1 gene. Expression of this gene appears insensitive to some of the environmental stresses tested, which instead up-regulate other members of the Arabidopsis ferritin gene family.
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PMID:Differential involvement of the IDRS cis-element in the developmental and environmental regulation of the AtFer1 ferritin gene from Arabidopsis. 1272 19

Iron (Fe) is an essential element for living organisms. However, under aerobic conditions, its use is complicated because of its high insolubility and its potential toxicity through reactivity with reduced forms of oxygen. In plants, Fe overload can lead to intracellular concentrations beyond the storage and detoxification capacities of cells. Such a displacement toward a pro-oxidant state can activate antioxidant defenses, including Fe-mediated expression of ascorbate peroxidase genes. In this work, we demonstrate that Fe overload specifically induces the AtAPX1 gene encoding a cytosolic ascorbate peroxidase in Arabidopsis leaves. The strong constitutive expression of the AtAPX1 gene in roots is unaffected by Fe and depends on the first 5'-untranslated region intron. Presence of an AtAPX1 expressed sequence tag in the Arabidopsis database, longer in its 5' region than what could be predicted from the published AtAPX1transcription initiation site, leads to define a new transcription initiation region for this gene. A minimal promoter sequence enabling Fe-induced expression of the AtAPX1 gene is defined by following expression of various AtAPX1::beta-glucuronidase constructs in transformed Arabidopsis plantlets. This 118-bp minimal promoter sequence contains an Fe-dependent regulatory sequence-like cis-element known to be necessary for maize (Zea mays) and Arabidopsis ferritin gene derepression in response to Fe overload. Site-directed mutagenesis of this element within the AtAPX1 promoter sequence does not abolish the Fe-dependent activation of a reporter gene, indicating that it is likely not involved in the Fe-regulated expression of the AtAPX1 gene.
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PMID:Iron-regulated expression of a cytosolic ascorbate peroxidase encoded by the APX1 gene in Arabidopsis seedlings. 1473 45