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

New immunochemical reagents consisting of antibodies bound to small latex spheres were used as visual markers for the detection and localization of cell surface antigens by scanning electron microscopy. Cross-linked latex spheres of various sizes from 300 to 3,4000 A in diameter were synthesized by aqueous emulsion copolymerization of methacrylate derivatives containing hydroxyl and carboxyl functional groups. Proteins and other molecules containing primary amino groups were covalently bonded to the acrylic spheres under a variety of mild conditions by the aqueous carbodiimide, cyanogen bromide, and glutaraldehyde methods. For use in the indirect immunochemical-labeling technique, goat antibodies directed against rabbit immunoglobulins were bonded to the spheres. These immunolatex reagents were shown to bind only to cells (red blood and lymphocytes) which had previously been sensitized with rabbit antibodies against cell surface antigens. Mouse spleen lymphocytes with exposed immunoglobulins on their surface (B cells) were labeled with these spheres and distinguished from unlabeled or T lymphocytes by scanning electron microscopy. The distribution of Ig receptors on lymphocytes was also studied using the spheres as visual markers. When lymphocytes were fixed with glutaraldehyde and subsequently labeled with the immunolatex reagents, a random distribution was observed by scanning electron microscopy; a patchy distribution was observed when unfixed lymphocytes were used. These results are consistent with studies using ferritin-labeled antibodies (S. De Petris and M. Raff. 1973. Nature [Lond.]. 241:257.) and support the view that Ig receptors on lymphocytes undergo translational diffusion. In addition to serving as visual markers for scanning electron microscopy, these latex spheres tagged with fluorescent or radioactive molecules have applications as highly sensitive markers for fluorescent microscopy and as reagents for quantitative studies of cell surface antigens and other receptors.
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PMID:New immunolatex spheres: visual markers of antigens on lymphocytes for scanning electron microscopy. 80 28

Ferritins from human liver, spleen, heart, pancreas and kidney were compared by electrophoresis and isoelectric focusing in polyacrylamide gels, by immunodiffusion against antisera to homologous and heterologous ferritin, and in some cases by their cyanogen bromide peptides. All ferritins appeared to consist of a single species on gel electrophoresis with the exception of heart ferritin which separated into two major components. Small differences in electrophoretic mobility were found in all tissue ferritins. By contrast, all tissue ferritins were found to consist of multiple forms when analysed by gel electrofocusing. At least five isoferritins were found in most tissues, several of which were common to most tissues. At least two were common to all tissues. Those ferritins which were most easily distinguishable electrophoretically, e.g. spleen and heart ferritin, showed the greatest differences on gel electrofocusing. The ferritin profile was characteristic of each organ and was reproducible both within individuals and between individual tissues. There were striking differences in the iron content of the various isoferritins within a tissue. Further, the iron content of isoferritins common to more than one tissue varied with the tissue of origin. Some isoferritins in several organs and all of the isoferritins in pancreas appeared to contain little, if any, iron. All five tissue ferritins contained antigenic determinants in common with liver ferritin. However, an additional antigenic determinant was found in liver ferritin which was not detectable in the ferritins from the other organs.
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PMID:Human isoferritins: organ specific iron and apoferritin distribution. 81 Dec 43

Bromadiolone damaged the erythrocytes, resulting in a probable saturation of transferrin, a deposit of iron in the connective tissue and in a few cells of the proximal tubules of the kidneys and an increased storage of ferritin in the spleen. In the hepatocytes, mitochondria were distorted, their lipid inclusions being granular; a large depletion of glycogen may be considered a reflection of an elevated phosphorylase a ascribable to the proliferation of the smooth endoplasmic reticulum. In the kidneys, pyelonephritis may be irrelevant to the poisoning of the animals. Bromine could not be detected using microanalytical methods.
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PMID:[Effects of bromadiolone on some organs and tissues (liver, kidney, spleen, blood) of coypu (Myocastor coypus)]. 190 55

Intravaginal (ivag) immunization elicits secretory immune responses in the female reproductive tract, but little is known about the safety and effectiveness of adjuvants for such immunization. Mice were immunized intravaginally once daily for 5 days with large doses of horse ferritin combined with aluminum hydroxide (AH), muramyl dipeptide (MDP), monophosphoryl lipid A (MPL), dimethyl dioctadecyl ammonium bromide (DDA) or cholera toxin (CT). Titers of anti-ferritin IgA and IgG were measured in vaginal fluid by ELISA. The most effective adjuvant for ivag primary immunization was AH, while MPL was most effective for ivag boosting. None of the adjuvants caused a detectable tissue reaction in vaginal mucosa. Primary ivag immunization for 5 days with ferritin and AH followed by ivag boosting for 5 days with ferritin and MPL elicited higher IgA titers in vaginal fluid than systemic priming and boosting with ferritin and AH or systemic priming and ivag boosting with ferritin and MPL. Systemically immunized animals exhibited the highest IgG titers in vaginal fluid. The data indicate that adjuvants, particularly AH, can increase local immune responses to intravaginal immunization, but it should be noted that multiple applications of large doses of antigen were used and that this route of sensitization may be relatively inefficient.
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PMID:The effect of adjuvants on antibody titers in mouse vaginal fluid after intravaginal immunization. 221 22

Intravaginal immunization causes IgA responses in vaginal fluid, but so far lymphoid nodules in mouse vaginal mucosa have not been detected. The present study was therefore designed to test the hypothesis that IgA responses in the female reproductive tract may be generated in the regional iliac lymph nodes. Two, non-mucosal sites were identified in the female mouse pelvis, the subserous and presacral spaces, from which lymph drains mainly to the iliac nodes. Immunization at these pelvic sites with horse ferritin adsorbed to aluminum hydroxide (AH) caused much higher IgA and IgG titres in vaginal fluid than intravaginal immunization; moreover, the pelvic immunizations caused significantly higher and better sustained IgA titres in vaginal fluid than subcutaneous immunization near the scapulae or in the perineum, while IgG titres in vaginal fluid were similar in these groups. Additional mice were immunized with ferritin subcutaneously near the scapulae or in the presacral pelvic space using dimethyl dioctadecyl ammonium bromide (DDA), AH plus muramyl dipeptide, or the Ribi adjuvant system as adjuvants. Pelvic immunization caused higher IgA titres in vaginal fluid than subcutaneous immunization in each case. The IgA response stimulated by DDA was similar to that produced by AH but higher than the responses caused by the other two adjuvants, while IgG titres were similar with all four adjuvants in both sites. The results suggest that non-mucosal, pelvic immunization is particularly effective in stimulating IgA responses in the female reproductive tract. The observation is consistent with the possibility that the iliac lymph nodes may play a role in the development of IgA responses in the reproductive tract.
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PMID:Secretory immune responses in mouse vaginal fluid after pelvic, parenteral or vaginal immunization. 235 56

Ferritin is a multisubunit protein, controlling iron storage, with a protein coat composed of 24 subunits (up to three distinct types) in different proportions depending on cell type. Little is known about the subunit interactions in ferritin protein coats composed of heterologous subunits, despite the relevance to ferritin structure and ferritin function (iron uptake and release). Synthetic crosslinking is a convenient way to probe subunit contacts. Crosslinks between subunit pairs in ferritin protein coats are also a natural post-translational modification which coincides with different iron content in ferritin from sheep spleen; ferritin from sheep spleen also contains H and L subunits. Crosslinks synthesized by the reaction of ferritin low in natural crosslinks with difluorodinitrobenzene (F2DNB) reproduced the effects of the natural crosslinks on iron uptake and release. We now extend our observations on the structural effects of natural and synthetic crosslinks to include immunoreactivity of the assembled protein, with monoclonal antibodies as a probe. We also demonstrate, for the first time, ferritin peptides involved in an apparent H- and L-subunit contact: two peptides decreased 4X in cyanogen bromide peptide maps after F2DNB crosslinking were residues L-96-138 and H-66-96; the major DNP-dipeptide was Lys-DNP-Lys. Using the structure of an all L-subunit ferritin as a model, the most likely site for the H-L DNP crosslink is L-Lys 104 (C helix) and H-Lys 67 (B helix). The B helix forms the internal subunit dimer interface, a putative site of iron core nucleation. Alteration by crosslinks of the B helix could, therefore, explain the effect of crosslinks on ferritin iron uptake, release, and iron content.
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PMID:Crosslinks between intramolecular pairs of ferritin subunits: effects on both H and L subunits and on immunoreactivity of sheep spleen ferritin. 247 18

The enamel organ of growing rat incisors was perfusion-fixed with a mixture of formaldehyde and glutaraldehyde and processed for ultracytochemical demonstration of ouabain-resistant, K+-stimulated p-nitrophenylphosphatase representing the second dephosphorylative step of H-K-ATPase by use of the one-step lead method. Throughout the stages of amelogenesis, the enzymatic activity was found in the plasma membranes, mitochondrial membranes, and lysosomal structures of the cells of stratum intermedium, papillary layer, and ameloblast layer. Gap junctions and desmosomes between these cells were, however, free of reaction product or showed slight precipitates of reaction. The stellate reticulum and the outer enamel epithelium at the stage of enamel secretion were usually negative for reaction. Although secretory, transition, and ruffle-ended maturation ameloblasts showed enzymatic activity at their basolateral cell surfaces, their distal cell surfaces facing the enamel were always free of reaction product. On the other hand, the smooth-ended maturation ameloblasts seldom showed a positive reaction, except in lysosomes and along their basal cell surfaces. An energy-dispersive X-ray microanalysis of reaction products of H-K-ATPase in unosmicated tissue sections demonstrated that they were composed of lead and phosphorus, which had been released during the dephosphorylation of substrate. In cytochemical controls, the enzymatic activity was completely dependent on substrate and potassium ion, resistant to ouabain and levamisole, and inhibited by nolinium bromide, a specific inhibitor of H-K-ATPase. In addition, inorganic trimetaphosphatase as enzymatic marker of lysosome was localized in dark and pale lysosomes, phagosomes, multivesicular bodies, and ferritin-containing vesicles of the ameloblasts and the cells of stratum intermedium and papillary layer. These membrane-bound structures were also positive for H-K-ATPase reaction. These results suggest that: 1) H-K-ATPase functions to maintain an acidic internal pH of lysosomes in the enamel organ cells; and 2) H-K-ATPase localization in the plasma membranes of enamel organ cells is concerned with efflux of protons derived from cytoplasmic water.
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PMID:H+-K+-ATPase activity in the rat incisor enamel organ during enamel formation. 284 91

The major glycoprotein of the human erythrocyte membrane has been isolated by treatment with lithium di-iodosalicylate and found to be a single polypeptide chain with a molecular weight of about 50,000. This molecule, which is 60% carbohydrate and 40% protein, carries multiple blood-group antigens, the receptors for influenza viruses, and various plant agglutinins. Four unique carbohydrate-containing peptides (alpha-1, alpha-2, alpha-3, and beta) are produced by tryptic digestion of the isolated glycoprotein; their order in the molecule has been determined by sequential tryptic digestion of intact erythrocyte membranes and partially digested glycoprotein fragments. Cleavage of the native protein with cyanogen bromide produces five fragments; two of these (C-5 and C-1) contain most of the carbohydrate in the molecule and are derived from the N-terminal half of the polypeptide chain. The nonpolar amino acids of this glycoprotein are located predominantly in the C-terminal fragment (C-2). Phytohemagglutinin conjugated to ferritin has been used to map the distribution of glycoprotein receptors over the surfaces of intact erythrocytes by freeze-etching and electron microscopy. This label localizes to sites on the membrane that overlie the intramembranous particles. These findings suggest that the glycoprotein is oriented at the cell surface with its oligosaccharide-rich N-terminal end exposed to the exterior, while its C-terminal segment interacts with other components in the interior of the membrane to form intramembranous particles.
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PMID:Chemical characterization and surface orientation of the major glycoprotein of the human erythrocyte membrane. 450 56

Ferritin, an iron-storage protein found in all life forms examined, is composed of varying proportions of two subunits of different molecular weight, heavy (H) and light (L). Using cDNA clones, we have determined the nucleotide sequence corresponding to the mRNA of the L-subunit of rat liver ferritin. The coding region of 546 nucleotides (182 amino acids) is flanked by 5'- and 3' -untranslated regions of approximately 130 and 150 nucleotides, respectively. The rat liver L-subunit amino acid sequence derived from the reading frame of the cDNA showed 88% and 82% homology, respectively, with the amino acid sequences of horse spleen ferritin (Heusterspreute, M., and Crichton, R. R. (1981) FEBS Lett. 129, 322-327), and human spleen ferritin (Wustefeld, C., and Crichton, R. R. (1982) FEBS Lett. 150, 43-48), thus demonstrating evolutionary conservation of the L-subunit sequence. However, a major difference between the rat and the horse and human sequences is the insertion of an octopeptide near the COOH-terminus of the rat protein resulting in a slightly longer peptide chain in this species. The reading frame and parts of the derived amino acid sequence including the octopeptide sequence were confirmed by direct amino acid sequencing of cyanogen bromide peptides from rat liver ferritin. Minor fragments of rat liver ferritin, presumably derived from the H-subunit, were also isolated after cyanogen bromide treatment. On sequencing, these H-peptides showed limited homology with regions of the L-sequence but extensive homology with published H-sequences from human liver and spleen. The H-subunit sequence did not contain the octopeptide found as part of the L-subunit sequence.
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PMID:Conservation in rat liver of light and heavy subunit sequences of mammalian ferritin. Presence of unique octopeptide in the light subunit. 654 56

Ferritin with high and low iron content, 2000 and 790 iron atoms/molecule, was isolated from the spleens of copper-poisoned and control lambs, respectively. Differences in the iron content in vivo were reflected in the properties of the apoferritin protein shells, since the apoprotein from the low iron ferritin took up iron relatively more slowly (0.52 +/- 0.09) and released it more rapidly (1.68 +/- 0.06) in vitro. Although the two types of apoferritin were indistinguishable in terms of surface charge (pI range 4.98-5.43) and in consisting of both heavy and light subunits, the subunit interactions differed markedly; 40-50% of the subunits of low iron ferritin were in dimers stable to reduction and carboxylmethylation, 4% mercaptoethanol, 8% sodium dodecyl sulfate, and 100 degrees C for 30 min, 70% formic acid, and 30% methanol. Subunit dimers were also observed in liver ferritin from mouse and neonatal pig and were enriched in a low iron fraction of horse spleen ferritin. Based on cyanogen bromide fragmentation and NH2-terminal analysis, the natural and chemically cross-linked subunit dimers had two peptides in common; natural subunit dimers also appeared to have a second region cross-linked, suggesting the possibility of both intra- and intersubunit links in the natural dimers. In sheep spleen ferritin, both heavy and light subunits appeared to participate in subunit dimerization. Natural subunit dimers were enriched in low iron ferritin fractions of all ferritin preparations tested (linear correlation = 0.94) and can explain, at least in part, the previously observed effects of iron core size on the apoferritin shell. Whether the subunit cross-links represent part of the subunit assembly process subsequently cleaved by iron (or copper) or whether the cross-links form after iron core formation in vivo has yet to determined. In either case, it is clear that such post-translational variations can affect iron uptake and release and emphasize the importance of the protein shell in determining the iron storage properties of ferritin.
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PMID:Subunit dimers in sheep spleen apoferritin. The effect on iron storage. 661 39


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