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

Lipid peroxide formation was initiated by the addition of either ADP-complexed Fe3+ or cumene hydroperoxide to a suspension of isolated hepatocytes. The reaction was monitored by malonaldehyde measurements. Upon the addition of iron, malonaldehyde production in the cells started immediately but ceased within 30-60 min, and the response was dose-related with iron concentrations ranging from 19 to 187 muM. Malonaldehyde formation was associated with increased oxygen uptake and conjugated diene production. The addition in vitro of N,N,N',N'-tetramethyl-p-phenylenediamine, menadione or p-benzoquinone inhibited the iron-induced malonaldehyde production. It was also possible to demonstrate an apparent disappearance of malonaldehyde from fresh cells by addition of adequate amounts of N,N,N',N'-tetramethyl-p-phenylenediamine (100 muM). The attenuation of the iron-induced malonaldehyde production was found to be correlated with an increased binding of iron to an intracellular ferritin fraction. Further, malonaldehyde formation was also associated with a conversion of reduced glutathione to the oxidized form which, in turn, revealed a faster permeation out of the cells into the surrounding medium of the oxidized than of the reduced thiol. So, concomitant with the redox alterations, there was also an overall loss of glutathione from the cells. Cumene hydroperoxide-induced malonaldehyde production could be initiated by the addition of this peroxide in concentrations ranging from 150 muM to the liver cell incubate. With concentrations below 150 muM, a lag phase was present which seemed to be glutathione-dependent. It is concluded that iron enters the cell, then is probably reduced inside the cell by NADPH via the NADPH-cytochrome P-450 reductase, and in the reduced state initiates lipid peroxidation. The reaction is inhibited by intracellular mechanisms, the glutathione redox system being of principal importance, and possibly terminated by the iron-apoferritin complex formation.
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PMID:Further studies on lipid-peroxide formation in isolated hepatocytes. 0 Dec 55

A method is described which permits the detection of isoferritins in normal human serum and tissues. The technique makes use of 125I-labelled monospecific anti-human-liver-ferritin antibody to demonstrate the isoferritins after isoelectric focussing of the purified ferritin in polyacrylamide gels. The organ-specific variation in tissue isoferritin profile previously reported in normal subjects has been confirmed by this technique using only 50 ng of each ferritin sample. Serum ferritin from normal healthy subjects was also shown to exhibit a microheterogeneity on isoelectric focussing; six clearly defined isoferritin peaks were detected in the pH range of 5.04 to 5.62. This isoferritin profile of normal serum contained isoferritins over the whole range of the various tissue isoferritins suggesting that a number of organs may contribute to the normal serum ferritin pool.
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PMID:Immunological detection of isoferritins in normal human serum and tissue. 0 2

Combined morphological and analytical studies with the EMMA-4 analytical electron microscope have enabled very early erythroid cells to be identified within the cortex of enlarging thymic lobes of Quelea quelea. These early erythroid cells have pale cytoplasm (sometimes with ferritin-like crystals present), slightly pachychromatic nuclei and have fewer cell organelles (mitochondria) than lymphocytes. Counts for iron were approximately 70% lower than counts from mature erythrocytes found free in the cortex. Iron was also recorded from some epithelial reticular cells and pyknotic nuclei; no iron was recorded from small lymphocytes (thymocytes) in the cortex. The presence of very early erythroid cells is a further indication that erythropoiesis occurs in situ in the avian thymus.
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PMID:EMMA-4 analysis of iron in cells of the thymic cortex of a weaver-bird (Quelea quelea). 0 12

Chelating agents disrupted the superficial layers on Spirillum putridiconchylium and adsorption of cationized ferritin indicated that both upper and lower surfaces of superficial layer fragments, as well as the outer membrane surface, possessed areas which were negatively charged. Growth of the bacterium in 1% casamino acids (vitamin free) resulted in cells which were devoid of the superficial layers, and negative staining of these cells revealed in amorphous precipitate together with a vesicular outer membrane component extruding from their surfaces into the medium. Addition of either 1 mM Ca2+ or 1 mM Sr2+ to the growth medium produced the typical regularly structured cell surface, whereas addition of equal concentrations of Li+, Na+, K+, Mg2+, Ba2+, Mn2+, Fe3+, or three polyamines produced the structureless surface.
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PMID:Dependence of the superficial layers of Spirillum putridiconchylium on Ca2+ or Sr2+. 1 67

The interactions of horse spleen ferritin and its derivative apoferritin with H+ ions were studied by potentiometric and spectrophotometric titration; to aid in data analysis, heats of ionization over a limited pH range and amide content were also determined. Per apoferritin subunit, all tyrosine and cysteine side chains, two of the nine lysine side chains and at least three of the six histidine side chains were found not to titrate; a preliminary but self-consistent analysis of the titration data is proposed. The titration curve of ferritin was identical with that of apoferritin in the pH range 5.5 to 3. In addition, under the conditions used, the reactivities of ferritin histidines to bromoacetate and of ferritin lysines to formaldehyde were identical with those in apoferritin. Above pH 8, a time-dependent titration of the ferritin core occurs which prevents comparison of the titration curves of the two proteins in this region. However, in the pH regions 5.5 to 7.5, two extra groups per subunit titrate reversibly in ferritin relative to apoferritin. Moreover, although the isoionic points of ferritin and apoferritin are identical in water, the isoionic point of ferritin is 0.5 pH unit lower than that of apoferritin in 0.16 to 1 M KCl. The different effects of KCl and NaCl on the two proteins indicate the presence of cation binding sites in ferritin that are absent in apoferritin and possibly also the presence of anion binding sites in apoferritin that are occupied in ferritin by anions of the core. The difference between the isoionic points of the two proteins in KCl has been interpreted to indicate the presence of approximately 2 phosphate residues per ferritin subunit which serve as cation binding sites and which are negatively charged at the isoionic point in KCl. These phosphates may also represent the additional residues that titrate in ferritin between pH 5.5 and 7.5, or may interact with positively charged residues on the inner surface of the ferritin shell, or both.
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PMID:Hydrogen ion interactions of horse spleen ferritin and apoferritin. 1 Dec 12

A highly sensitive technique for isoferritin detection using 125I-labeled monospecific anti-human liver ferritin antibody for the identification of isoferritins after the analysis of small quantities of ferritin by isoelectric focusing in polyacryl-amide gels was applied to the study of renal, pancreatic, and colonic carcinomas. In all tumors studied, the isoferritin composition differed from that of the corresponding normal tissue; major isoferritins with pl more basic than those of the normal tissues were consistently detected. Composition of purified ferritin from metastases closely resembled the isoferritin composition of the primary tumors. Examination of the serum isoferritin profiles of four patients with cancers did not reveal the presence of any tumor-specific changes in isoferritins. It is suggested that the abnormality in tissue ferritins in the three human cancers studied is the synthesis of major isoferritins in the more basic range, rather than the appearance of tumor-specific isoferritins in the more acidic range.
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PMID:Isoferritin composition of tissues and serum in human cancers. 1 86

Immunologic mechanisms of proteinuria were investigated in guinea pigs (GP) injected with sheep antiserum (NTS) to GP glomerular basement membrane (GBM). Linear deposition of sheep gamma 1 and gamma 2 IgG led to a prompt but transient (36 hr) increase in albumin excretion from control values of 0.026 +/- 0.013 mg/hr to maximal values of 26+/-12.1 mg/rh at six hours without detectable histologic or electron microscopic changes except for decreased staining for glomerular polyanion and epithelial cell foot process fusion. GBM permeability to anionic ferritin was not increased during proteinuria. Anti-GBM antibody deposits did not fix GP C3 or C4 in vivo or in vitro. NTS-induced proteinuria was the same in guinea pigs that were normal, greater than 95% depleted of C3 through C9, genetically deficient in C4, and depleted of circulating polymorphonuclear leukocytes (PMN). Prior administration of antihistamines, steroids, azathioprine, colchicine, indomethacin, heparin, aprotinin (Trasylol), and niridazole also failed to reduced proteinuria. Initial proteinuria subsided by 36 hr, did not recur despite linear deposition of GP gemma 1 and gemma 2 after day seven, and antibody to GMB-bound sheep globlin. In the GP nephrotoxic nephritis model, anti-GBM antibody deposits apparently mediate increased permeability to albumin by a currently undefined mechanism which is independent of complement, PMN, and other know mediators of inflammation.
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PMID:Complement-independent nephrotoxic nephritis in the guinea pig. 1 57

The isoferritin composition of serum ferritin in 13 patients with untreated idiopathic haemochromatosis (IHC) has been shown to differ from normal in exhibiting an increase in isoferritins in the pH range 5.54-5.62. A similar change was observed in four patients with gross iron overload secondary to haemolytic anaemia. During the course of venesection therapy there was a progressive rise in isoferritins of pI 5.02-5.06 relative to the more basic isoferritins. These observations are consistent with previous studies showing alterations in tissue isoferritins in untreated IHC before and after venesection therapy and they are compatible with the hypothesis that the more basic isoferritins correspond to a 'storage' ferritin and the more acidic to a 'secretory' ferritin. The studies also provide further evidence for a possible biological role of the individual isoferritins.
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PMID:Serum ferritin in haemochromatosis: changes in the isoferritin composition during venesection therapy. 1 30

Previous studies with protein tracers have shown that the luminal surface of the vascular endothelium of the bone marrow is endocytic. The endocytosis occurs through the formation of large bristle-coated vesicles (LCV). The anionic charge distribution in this process was examined at the luminal surface of the endothelial cell, At pH 1.8, colloidal iron (CI), native ferritin, and polycationic ferritin (PCF) are bound by the luminal surface of the endothelial cell, but not at the sites of LCV formation. PCF used over a pH range of 1.8--7.2 (CI is unstable at higher pH levels) revealed LCV binding of this agent in increasing manner from pH 3.5 upwards. PCF binding at low pH (1.8) at the endothelial cell surface was markedly reduced by neuraminidase. Neuraminidase did not reduce PCF binding by the endothelial cell surface nor by the LCV at higher pH levels. It is concluded that the luminal surface of the endothelial cell has exposed sialic acid groups which are absent or significantly diminished at endocytic sites. The free surface of the endothelial cells as well as the sites of endocytosis have, in addition, anionic material with a pKa higher than that of sialic acid (pKa 2.6). These anionic materials may be different at the sites of endocytosis as compared to those present at the free cell surface.
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PMID:Nonrandom distribution of sialic acid over the cell surface of bristle-coated endocytic vesicles of the sinusoidal endothelium cells. 2 50

Acute lowering of blood pH between 7.4 and 6.9 in rats by ventilation with 10 or 20% CO2 does not increase the passage of ferritin molecules across the aortic endothelium. These results do not rule out alteration of endothelial permeability to anionic macromolecules in local circulatory disturbances when blood pH drops to levels much lower than 6.9.
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PMID:Effect of blood pH on anionic ferritin transport through rat aortic endothelium. 3 Dec 96


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