Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A carbohydrate-containing fraction was extracted from the trypanosomatid Crithidia fasciculata by a phenol-water procedure. Ion-exchange chromatography separated this fraction into three components: a polysaccharide which was not retained on the column; RNA which eluted upon addition of salt; and, another polysaccharide which eluted upon addition of detergent. The unretained fraction was shown to be composed solely of D-mannose. The mannan, which was heterodisperse on Sephadex G-100, had an average molecular weight of approx. 14 000 as based on analysis of reducing groups. The detergent-eluted material yielded arabinose and galactose upon acid hydrolysis. The arabinogalactan was excluded from Sephadex G-100 and Sephacryl S-200 molecular sieve columns, suggesting a molecular weight greater than or equal to 200 000. Cell fractionation studies showed the bulk of extractable polysaccharide was associated with a particulate fraction. Further determination of the cellular localization of the polysaccharide was accomplished by employing a specific antiserum prepared from rabbits immunized with the polysaccharide extract. The cell surface localization of the arabinogalactan was demonstrated by cell agglutination studies as well as immunocytochemical techniques using fluorescein and ferritin conjugated antibodies.
 ...
PMID:Polysaccharides of crithidia fasciculata. Identification and partial characterization of a cell surface constituent. 9 71

Carbohydrate-containing structures in rat liver rough microsomes (RM) were localized and characterized using iodinated lectins of defined specificity. Binding of [125I]Con A increased six- to sevenfold in the presence of low DOC (0.04--0.05%) which opens the vesicles and allows the penetration of the lectins. On the other hand, binding of [125I]WGA and [125I]RCA increased only slightly when the microsomal vesicles were opened by DOC. Sites available in the intact microsomal fraction had an affinity for [125I]Con A 14 times higher than sites for lectin binding which were exposed by the detergent treatment. Lectin-binding sites in RM were also localized electron microscopically with lectins covalently bound to biotin, which, in turn, were visualized after their reaction with ferritin-avidin (F-Av) markers. Using this method, it was demonstrated that in untreated RM samples, binding sites for lectins are not present on the cytoplasmic face of the microsomal vesicles, even after removal of ribosomes by treatment with high salt buffer and puromycin, but are located on smooth membranes which contaminate the rough microsomal fraction. Combining this technique with procedures which render the interior of the microsomal vesicles accessible to lectins and remove luminal proteins, it was found that RM membranes contain binding sites for Con A and for Lens culinaris agglutinin (LCA) located exclusively on the cisternal face of the membrane. No sites for WGA, RCA, soybean (SBA) and Lotus tetragonobulus (LTA) agglutinins were detected on either the cytoplasmic or the luminal faces of the rough microsomes. These observations demonstrate that: (a) sugar moieties of microsomal glycoproteins are exposed only on the luminal surface of the membranes and (b) microsomal membrane glycoproteins have incomplete carbohydrate chains without the characteristic terminal trisaccharides N-acetylglucosamine comes from galactose comes from sialic acid or fucose present in most glycoproteins secreted by the liver. The orientation and composition of the carbohydrate chains in microsomal glycoproteins indicate that the passage of these glycoproteins through the Golgi apparatus, followed by their return to the endoplasmic reticulum, is not required for their biogenesis and insertion into the endoplasmic reticulum (ER) membrane.
 ...
PMID:Spatial orientation of glycoproteins in membranes of rat liver rough microsomes. I. Localization of lectin-binding sites in microsomal membranes. 70 63

The presence of iron in articular cartilage was investigated in five human and two canine cases of factor VIII-deficiency hemophilic arthropathy. The lesions were mild in three cases. Advanced destruction of the cartilage was present in four cases, in one of which sufficient cartilage was preserved to permit recognition of hemosiderin in chondrocytes. The Fe was present in the form of siderosomes and ferritin granules free in the cytoplasm. Iron and phosphorus were demonstrated in the siderosomes by energy dispersion analysis of x-rays; but no Fe was identified by this means or by light or transmission electron microscopy in chondrocytes from the three subjects in an early stage of the disease or in the matrix from any of the seven subjects. The findings lend no support to the hypothesis that salt formation or chelation of Fe ions by matrix proteoglycans is responsible for destruction of cartilage in hemophilic or other chronic hemarthroses. A second, nonferruginous, bilirubin-like pigment (hematoidin) was present in the matrix at the surface of the cartilage in two specimens.
 ...
PMID:Cartilage in hemophilic arthropathy. Ultrastructural and microanalytical studies. 94 96

In the present state of our knowledge it must be concluded that the outstanding anatomic changes directly attributable to acute iron poisoning are in the gastrointestinal tract and the liver. Both seem to be due to the direct action of iron upon living cells. In the stomach and small bowel the changes appear to be due to the corrosive effect of the iron salt whether in solution or in tablet form. And the anion may indeed play the predominant role as demonstrated by the observation of the severe corrosive changes observed when accumulations of ferrous sulfate tablets occur in areas of the stomach or small bowel. That the mucosal barrier to iron is broken down seems incontrovertible. And it is no longer tenable to assume that the severe complications of iron poisoning are due to the local necroses in the gastrointestinal tract. The liver, being the first parenchymal organ encountered by absorbed iron, is involved to a varying degree. The anatomic changes can progress to frank necrosis in severe cases. And even in those where overt histologic damage is not demonstrable, alterations in biochemical function occur. Anatomic changes in other parenchymal organs are probably largely secondary to dehydration, shock, hemorrhage, and infection. But the possibility of disordered enzyme systems here as well must be borne in mind though so far not demonstrated. In severe cases where hemorrhages play so large a role, albeit infrequently, the specific action of iron in interference with coagulation mechanisms is of the utmost importance. The role of therapy with deferoxamine in production of shock is discussed below. In this connection breakdown of the mucosal barrier with release of apoferritin and ferritin as a hypotensive mechanism has also been suggested by Smith.
 ...
PMID:Iron poisoning in children. 122 66

In order to reassess the need for iron chelation therapy in nontransfused patients with beta-thalassemia intermedia, serum ferritin level and ferrous iron absorption from the gastrointestinal system were measured in 43 (23 male and 20 female) patients (mean age 13.4 +/- 7.5). The mean hemoglobin value was 8.6 +/- 1.3 g/dL and serum ferritin 303 +/- 207 ng/mL. Absorption of ferrous iron salt was determined in 21 patients by measuring serum iron before and 3 hours after giving ferrous salt orally at 1 mg/kg. The means of the increase in serum iron values were 39 +/- 45, 105 +/- 46, and 224 +/- 112 micrograms/dL in patients with beta-thalassemia intermedia, normal subjects, and patients with iron deficiency anemia respectively. Differences in the means in three groups were significant (p < 0.001). This study shows that iron absorption from the gastrointestinal system as ferrous salt is not accelerated in patients with beta-thalassemia intermedia. The serum ferritin level in these patients is not high enough to necessitate iron chelation therapy.
 ...
PMID:Reevaluation of iron absorption and serum ferritin in beta-thalassemia intermedia. 146 69

Sodium chloride stimulated catalysis of oxidation of phosphatidylcholine liposomes by the soluble fraction of mackerel muscle. Chloride was determined to be the active component of the salt in this system. Sulfate also stimulated lipid oxidation. No difference was observed with either anion among sodium, potassium, or lithium cations. Redox iron was involved in the chloride stimulation of lipid oxidation by the press juice. Part of the chloride stimulation of the press juice was mediated through the high molecular weight (greater than 5 kdalton) fraction. Chloride improved the pro-oxidative effect of ascorbate on rat liver ferritin in vitro. It did not appear that production of chlorine radical by peroxidase was involved in the stimulatory effect of chloride.
 ...
PMID:Effect of NaCl on catalysis of lipid oxidation by the soluble fraction of fish muscle. 153 69

Ferritin is a typical intracellular protein but small amounts are also present in serum and other biological fluids. The source and physiological significance of serum ferritin are still obscure. The presence of ferritin mRNAs on polysomes bound to endoplasmic reticulum (ER) could be relevant for the secretion of ferritin. By Northern blot analysis we found significant amounts of both L and H subunit mRNAs on rat liver membrane-bound polysomes. Immunoprecipitation of translational products of membrane-bound polysomes with anti-rat liver ferritin antibody showed that ferritin is actually synthesized on ER membranes. Analysis of RNA extracted from salt-washed rat liver microsomes demonstrated that ferritin mRNAs are translated by polysomes tightly bound to ER membranes. Following iron treatment, both the amount of H and L subunit mRNAs and ferritin synthesis increased sharply in both free and bound polysomal fractions. Translation of membrane-bound polysomes in the presence of microsomal membranes indicated that ferritin is not processed by signal sequence cleavage or glycosylation and is not translocated into ER membranes. Ferritin mRNAs found on membrane-bound polysomes are associated with ER in a specific way, however, their products do not seem to follow the classic secretory pathway and therefore the significance of the large amount of ferritin mRNAs in the bound ribosome fraction remains unclear.
 ...
PMID:Ferritin mRNAs on rat liver membrane-bound polysomes synthesize ferritin that does not translocate across membranes. 161 Aug 92

Human ferritin, a multimeric iron storage protein, is composed by various proportions of two subunit types: the H- and L-chains. The biological functions of these two genic products have not been clarified, although differences in reactivity with iron have been shown. Starting from the hypothesis that the high stability typical of ferritin is an important property which may be relevant for its iron storage function, we studied ferritin homopolymers of H- and L-chains in different denaturing conditions. In addition we analyzed 13 H-chain variants with alterations in regions conserved within mammalian H-chains. In all the denaturation experiments H-chain ferritin showed lower stability than L-chain ferritin. The difference was greater in guanidine HCl denaturation experiments, where the end products are fully unfolded peptides, than in acidic denaturation experiments, where the end products are peptides with properties analogous to "molten globule." The study on H-chain variants showed: (i) ferritin stability was not affected by alterations of regions exposed to the inner or outer surface of the shell and not involved in intra- or inter-chain interactions; (ii) stability was reduced by alterations of sequences involved in inter-subunit interactions such as the deletion of the N-terminal extension or substitutions along the hydrophobic and hydrophilic channels; (iii) stability was increased by the substitution of 2 amino acids inside the four-helix bundle with those of the homologous L-chain. One of the residues is involved in a salt bridge in the L-chain, and we concluded that the stability difference between H- and L-ferritins is to a large extent due to the stabilizing effect of this salt bridge on the L-subunit fold.
 ...
PMID:Evidence that a salt bridge in the light chain contributes to the physical stability difference between heavy and light human ferritins. 162 7

Itai-itai disease is thought to be the result of chronic cadmium (Cd) intoxication. We examined 23 autopsy cases of itai-itai disease and 18 cases of sudden death as controls. Urine and blood samples from 10 patients were collected before they died and revealed the presence of severe anemia and renal tubular injuries. Undecalcified sections of iliac bone were stained with Aluminon reagent, and ammonium salt of aurintricarboxylic acid, and Prussian blue reagent in all cases of itai-itai disease. These two reagents reacted at the same mineralization fronts. X-ray microanalysis revealed the presence of iron at mineralization fronts in itai-itai disease. Five patients showed evidence of hemosiderosis in the liver, spleen, and pancreas, probably as a result of post transfusion iron overload. Renal calculi and calcified aortic walls were also stained with Prussian blue reagent in several patients. Neither ferritin nor transferrin were visualized at mineralization fronts in itai-itai disease by immunohistochemical staining. These results suggest that iron is bound to calcium or to calcium phosphate by a physicochemical reaction. A marked osteomalacia was observed in 10 cases of itai-itai disease by histomorphometry. Regression analyses of data from cases of itai-itai disease suggested that an Aluminon-positive metal inhibited mineralization and that renal tubules were injured. Since bone Cd levels were increased in itai-itai disease, it is likely that renal tubules were injured by exposure to Cd. Therefore, stainable bone iron is another possible aggravating factor for osteopathy in itai-itai disease, and a synergistic effect between iron and Cd on mineralization is proposed.
 ...
PMID:Iron as a possible aggravating factor for osteopathy in itai-itai disease, a disease associated with chronic cadmium intoxication. 203 51

We describe a simple method for the affinity purification of specific RNA-binding proteins. DNA sequences corresponding to the protein-binding site of the RNA are subcloned into an in vitro transcription vector between the T7 viral promoter and a poly(A) track. A polyadenylated RNA transcript is bound to poly(U)-Sepharose and subsequently incubated with a cellular extract prepurified on heparin-agarose. Specifically adsorbed proteins are recovered in high yield and purity from the affinity matrix by high salt elution. Using this method we isolated the iron regulatory factor (IRF), a cytoplasmic protein which binds to specific palindromic elements in the 5' and 3' untranslated sequences of ferritin and transferrin receptor mRNA, respectively. Activation and binding of this regulatory factor correlates with increased transferrin receptor mRNA stability and inhibition of ferritin translation. The purified factor from human placenta migrates as a monomer in gel chromatography, but is present in equimolar amounts of two proteins with molecular weights of 95 and 100 kDa when analysed by SDS/PAGE. The two proteins are highly related as judged by the identity of their isoelectric points and their specificity to form RNA-protein complexes.
 ...
PMID:A high yield affinity purification method for specific RNA-binding proteins: isolation of the iron regulatory factor from human placenta. 210 65


1 2 3 4 5 6 7 8 9 10 Next >>