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

Bovine serum IgG1, colostral IgG1 and serum IgG2 with anti-ferritin activity were digested with pepsin or trypsin. Their fragments were characterized by immunoelectrophoresis, gel electrophoresis and gel filtration; their ferritin-binding ability was determined. The kinetics of proteolysis were established by measuring the appearance of free amino groups. No differences were observed between serum and colostrum IgG1. IgG1 was more susceptible to pepsin, and IgG2 to trypsin. This became evident from both the amount of intact IgG determined by gel electrophoresis, immunoelectrophoresis or gel filtration, and from the kinetics of the appearance of amino groups. A model is presented to explain the size, mobilities and properties of the obtained fragments.
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PMID:Proteolysis of bovine immunoglobulins. 33 10

The chorionic villi of placentas, 10 to 40 weeks of gestation, were examined for A and B blood group antigens with an immunoferritin technique. No specific ferritin attachment was shown on the plasma membrane of the villous trophoblasts. Furthermore, after trophoblast cell-surface mucosubstances (perhaps the barrier of the placental antigenicity, according to some authors) were digested with several enzymes, such as neuraminidase, hyaluronidase, chondroitinase ABC, pepsin, trypsin, and pronase, no ferritin tagging was observed on the plasma membrane of the villous trophoblasts. We have concluded that our failure to detect the A and B blood group antigens was not due to the masking of antigens by mucosubstance coating the trophoblasts, but was due to the intrinsic deficit of those antigens in the plasma membrane of the human trophoblasts.
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PMID:Innumoelectron microscopy of the human chorionic villus in search of blood group A and B antigens. 79 65

Various lactoferrin preparations (iron-saturated and iron-depleted human milk lactoferrins and bovine milk and colostrum lactoferrins) were bound by Aeromonas hydrophila. Binding was (i) reversible (65% of bound lactoferrin was displaced by unlabeled lactoferrin), (ii) specific (lactoferrin but not other iron-containing glycoproteins such as ferritin, transferrin, hemoglobin, and myoglobin inhibited binding), and (iii) significantly reduced by pepsin and neuraminidase treatment of the bacteria. The glycosidic domains of the lactoferrin molecule seem to be involved in binding since precursor monosaccharides of the lactoferrin oligosaccharides (mannose, fucose, and galactose) and glycoproteins which have homologous glycosidic moieties similar to those of the lactoferrin oligosaccharides (asialofetuin or fetuin) strongly inhibited lactoferrin binding. A. hydrophila also binds transferrin, ferritin, cytochrome c, hemin, and Congo red. However, binding of these iron-containing compounds seems to involve bacterial surface components different from those required for lactoferrin binding. Expression of lactoferrin binding by A. hydrophila was influenced by culture conditions. In addition, there was an inverse relationship between lactoferrin binding and siderophore production by the bacterium.
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PMID:Characterization of lactoferrin binding by Aeromonas hydrophila. 131 45

A comparative study of rabbit IgG, both native and modified ones, designed to assess the functional activity of these proteins under oxidative iodination conditions has been carried out. Polyclonal IgG, its antigen-specific fraction and Iodogen as an oxidant were used. Polyclonal antibodies directed against the CH2 domain of IgG, protein A targeted at the CH-2-CH3 domain interface and ferritin testing the conformation of the antigen-binding Fv fragment, were applied as conformational probes for assessing the changes in the IgG conformation. By taking advantage of pepsin proteolysis of [125I]-IgG, from 80% to 92% of the label was found to be localized within the CH3 domain, thus implying the domain-selective nature of iodination, when the degree of modification was below 0.1 atom of iodine per IgG molecule. Yet, when the three above-mentioned conformational probes were used, considerable alterations in the conformation of not only the CH2 domain and CH2-CH3 domain interface, but in the Fv domain being a part of the Fab fragment, were observed. By using competitive enzyme immunoassay for the straightforward comparative evaluation of functional properties of "cold" (native) and 125I-modified IgG, the deleterious effect of the oxidant (Iodogen) rather than iodine atom substitution at the phenolic ring of Tyr residues was shown to be the major determinant of alterations in the IgG molecule.
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PMID:[Oxidative iodination of rabbit IgG: localization of markers in an Fc-fragment and effects of modification]. 174 12

Receptors for horse-spleen ferritin were found on group A streptococci. Both electron microscopic and chemical investigation of Streptococcus cells treated with ferritin showed that M + variants of group A streptococci were able to bind substantially more ferritin than M - variants of the same serotypes. Ferritin receptors were located on the tops of filamentous protrusions of Streptococcus cell walls and only on the outer surface of isolated cell walls. Trypsin treatment destroyed the ferritin-binding capacity of streptococci completely, while mild pepsin treatment left the ferritin receptors undisturbed, or uncovered additional ones. The ferritin receptors were not identical with receptors for the Fc-portion of swine IgG. The finding of ferritin receptors on bacteria necessitates careful interpretation of results obtained by immunoferritin localization techniques.
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PMID:Binding of horse-spleen ferritin to group A streptococci. 301 56

Human gallbladder and gastric epithelial cells are normally covered with a layer of mucus. When specimens were exposed to cationized ferritin (CF) in vitro, they did not regularly bind nor internalise it. If the tissues were first exposed to the mucolytic agents cysteamine or pepsin, then the gallbladder epithelium readily bound CF and the gastric epithelium irregularly. The in vivo binding of CF by guinea pig gallbladder could be abolished by the induction of mucous hypersecretion by the antibiotic lincomycin. The removal of the mucus by mucolytic agents restored the binding of CF. The irregular binding of CF by gastric mucosa after the use of mucolytic agents suggests other factors may be at play.
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PMID:The effects of mucus on the binding of cationized ferritin by human and animal gastrointestinal epithelium. 301

The location of lipoteichoic acid (LTA) on the surface of group A streptococci was studied by immunoelectron microscopic and ultrastructural cytochemical methods, i.e. by means of LTA antibodies labelled with ferritin, or concanavalin A labelled with ferritin or colloidal gold. All these methods proved the LTA to be located on the outer cell surface of most group A streptococcus strains. The differences in the intensity of labelling paralleled the hydrophobicity of the strains, being substantially higher in the strains exhibiting a high degree of hydrophobicity. Treatment of streptococci with pronase or trypsin led to a complete loss of surface-located LTA. On the other hand, pepsin treatment of streptococci under mild conditions resulted in an increased amount of surface-located LTA in some strains. On the isolated cell walls, LTA could be demonstrated only on the outer surface of the walls. These findings correlated well with the presumed role of group A streptococcus LTA in the adherence of streptococci to the epithelial cells which is accomplished with the aid of surface-located LTA molecules.
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PMID:Electron microscopic localization of lipoteichoic acid on group A streptococci. 305 68

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

Collagen VI is a large, disulfide-bonded protein complex which is widely distributed in connective tissue. The constituent polypeptide chains (Mr = 110,000-140,000) consist of collagenous and noncollagenous segments, are degraded to chains of about half the size when collagen VI is solubilized by pepsin, and assemble to a unique pattern of oligomers. As revealed by electron microscopy, the triple-stranded protomer consists of a triple helix 105 nm in length flanked on each side by globular domains of similar size (diameter about 7 nm). Protomers are assembled to dimers by an antiparallel staggered alignment of triple-helical segments. This leads to inner regions, 75 nm in length, of two slightly supercoiled triple helices flanked by globular domains. At both sides 30-nm-long outer triple-helical segments emerge that are terminated by globules. Tetramers are formed from laterally aligned dimers that cross with their outer triple-helical segments in a scissors-like fashion. The same structures, except with much smaller globular domains, are found in pepsin-treated collagen VI. Disulfide-linked collagen VI produced by cultured fibroblasts has a size similar to that of genuine collagen VI found in tissue extracts. Larger forms of collagen VI are assembled from tetramers by end-to-end aggregation which because of an overlap of the outer segments brings all globular domains close together. This arrangement predicts microfibrillar structures in tissues with a periodicity of 100-110 nm and a diameter of 5-10 nm. Structures consistent with this proposal were indeed found by immunoelectron microscopy of placenta and aorta using the ferritin technique. Large, lateral aggregates of collagen VI microfibrils may in addition exist in cell cultures and tissues ("zebra collagen," "Luse bodies") and are presumably maintained by contacts between globular domains.
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PMID:Structure and macromolecular organization of type VI collagen. 393 30

Eleven groups of workers submitted a total of 21 bronchial tumour-associated antigen preparations and 19 antisera for comparative studies. Many of the antisera proved to be polyspecific despite absorption procedures. Most of the antigen preparations contained some material reactive towards a reference antiserum to normal human serum proteins. While it appeared that no participants were studying identical antigen-antibody reactions, several cross-reactivities were identified in the antisera. When immune reactions to CEA, AFP, NCA, ferritin, lactoferrin, human pepsin and gastricsin, and the pregnancy proteins, SP1 and SP3 were excluded by use of reference antisera and electroimmunoprecipitation methods, there remained 5 antigen-antibody reactions defining unique antigens. The clinical usefulness of any of these 5 antigens has yet to be determined.
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PMID:Collaborative study of bronchial tumour-associated antigens. 617 Mar


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