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

Toxin A of Clostridium difficile was purified by column chromatography and acetic acid precipitation. Cells exposed to toxin A showed polarization of nuclei towards one pole of the cells. Toxin A was conjugated to ferritin and applied to L cells to localize binding sites of this toxin to the cell surface. It was found that toxin A conjugate attached to the cell membrane in aggregated form. Antibody specific to toxin A was prepared and used for localization of intracellular toxins in intoxicated cells. Toxin A was found inside the cytoplasm 6 h after cell treatment, mainly in the form of aggregates inside the cytoplasmic vacuoles. At 24 h after exposure, toxin A could be detected within the cytoplasm. Tunicamycin treatment of cells reduced the cell-binding efficiency of toxin A to 50%, but neuraminidase did not effect toxin binding significantly.
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PMID:Interaction of Clostridium difficile toxin A with L cells in culture. 647 12

The surface sialic acid content of aortic endothelial cells in vitro was substantially lower in sparse cultures than at confluence. Binding of LDL to endothelial cells did not change at different culture densities and was unaffected by brief pretreatment with neuraminidase to partially remove surface sialic acid residues. In contrast, internalization of LDL declined by a factor of 3 between low density cell cultures and confluent monolayers; neuraminidase pretreatment increased LDL uptake and the effect was most marked (greater than 10-fold) at confluence. Pretreatment with cationised ferritin, which removed most of the surface sialic acid residues as well as glycosaminoglycans, increased LDL internalization by up to 20-fold, again with most effect on confluent monolayers. Thus LDL uptake is inversely correlated with sialic acid content. We conclude that changes in the surface density of sialic acid (and possibly other charged) residues significantly modulate endothelial LDL uptake, and suggest that focal increases in LDL accumulation during atherogenesis may be related to alterations in endothelial endocytic properties at sites of increased cell turnover or damage.
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PMID:Surface determinants of low density lipoprotein uptake by endothelial cells. 649 41

Pseudopregnant, pregnant, and ovariectomized rabbits were utilized to study hormonal mediation of uterine epithelial surface negativity and glycocalyx morphology, and to seek local effects of blastocysts at sites of implantatioN. A loss of surface negativity [polycationic ferritin (PCF) binding] by day 6 of pregnancy or pseudopregnancy was noted, accompanied by alterations in epithelial glycocalyx. Uteri from estrous animals, or ovariectomized animals receiving oil or estradiol injections, bound PCF and exhibited a "globular" glycocalyx. Uteri from day 6 pseudopregnant or pregnant animals, or ovariectomized animals receiving progesterone injections, did not bind PCF or exhibit a globular glycocalyx. Both PCF binding and the globular character of the epithelial glycocalyx were sensitive to neuraminidase and trypsin treatment, suggesting sialoglycoprotein contribution to surface negativity. Implanting blastocysts had no detectable local effect on surface negativity, but did induce local reduction of epithelial glycocalyx at sites of implantation. Results of this study suggest that uterine epithelial glycocalyx alterations during the preimplantation period reflect a general response to progesterone stimulation, primarily qualitative in nature, related to the acquisition of receptivity to ovo-implantation.
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PMID:Alterations in epithelial glycocalyx of rabbit uteri during early pseudopregnancy and pregnancy, and following ovariectomy. 651 34

The surface charge of Leishmania mexicana amazonensis was evaluated by means of the binding of colloidal iron hydroxyde particles at pH 1.8 and cationized ferritin particles at pH 7.2 to the cell surface, visualizated by electron microscopy and by direct measurements of the electrophoretic mobility of cells suspended in solutions of different pH. The following forms of the parasite were analysed: amastigotes (surrounded or not by the membrane of the endocytic vacuole, isolated from lesions), transitional forms, and infective (5 passages) and noninfective (176 passages) promastigotes. The results obtained indicate that the surface of L. m. amazonensis contains both negatively and positively charged dissociating groups and that changes occur in the surface charge during amastigote-promastigote transformation. Treatment of the parasite with neuraminidase significantly reduced the electrophoretic mobility of the cells. Neuraminidase-treated cells recovered their normal electrophoretic mobility when incubated for 8 hr in fresh culture medium by a process that is inhibited by puromycin.
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PMID:Leishmania mexicana amazonensis: surface charge of amastigote and promastigote forms. 661 3

The bone-marrow sinusoidal endothelium is a cellular barrier that separates developing blood cells in the extravascular space from the peripheral circulation. Mature blood elements enter the circulation via transendothelial migration pores. In the present study, monosaccharide constituents on the bone marrow endothelium were examined using lectin-affinity cytochemistry. With lectin-horseradish and lectin-ferritin conjugates, mannosyl, N-acetylglucosaminyl, galactosyl, N-acetylgalactosaminyl, and sialic acid were localized to the luminal plasmalemma, bristle-coated pits and diaphragmed fenestrae. These were conspicuously reduced on the abluminal plasmalemma. When the tissue was treated with biotinylated lectins followed by avidin-ferritin, only a localization with wheat-germ agglutinin (sialic acid; N-acetylglucosaminyl) was observed. Pretreatment of the bone marrow with neuraminidase enabled the localization of the other monosaccharide components by the biotin-avidin method. Accumulations of carbohydrate residues were identified near the endothelium subjacent to migrating cells. Fucosyl moieties marked by Ulex europaeus agglutinin ( UEA ) reagents on the endothelium were not present. All binding was abolished by incubation of tissue and lectin conjugates with specific hapten sugars. labeling was also not present after Pronase E treatment, indicating that the identified monosaccharides are components of glycoproteins rather than glycolipids. The possible function of endothelial-surface glycoproteins as receptors for the surfaces of mature blood cells and their role in transmural migration are discussed.
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PMID:Ultrastructural localization of lectin receptors on the bone-marrow sinusoidal endothelium of the rat. 672 Jun 14

Primary turkey kidney cells and Eimeria meleagrimitis sporozoites were treated with cationized ferritin (CF) or neuraminidase ( NANase ), and the effects on the invasion of the cells by the sporozoites were measured. Cultures of host cells pretreated with either compound contained significantly fewer intracellular sporozoites than did control cultures. There was little additive effect if cultures were first treated with NANase and then with CF. In contrast, pretreatment of sporozoites with CF or low concentrations of NANase had no effect on invasion. The inhibition of invasion was apparently due to an interaction between treatment substances and host cell surface rather than to direct effect on the sporozoites. The CF bound to the randomly distributed anionic sites on the surfaces of both host cells and sporozoites and then rapidly aggregated. Sporozoites, probably in the process of invading cells, were invariably found with the conoid in close association with aggregates of CF on the host cell membrane. The CF on the sporozoites was apparently shed before or during invasion because all intracellular sporozoites were completely devoid of the label.
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PMID:Effects of cationized ferritin and neuraminidase on invasion of cultured cells by Eimeria meleagrimitis sporozoites. 673 15

Microtubules have been classified as either stable or labile, according to their resistance towards depolymerizing agents. The highest stability belongs to those organized in composite structures, in which many other proteins are associated with the tubulin. Among these microtubular systems, the marginal band of amphibian erythrocytes is unusually stable. This system can be readily isolated from Triturus red blood cells, and therefore lends itself very readily to ultrastructural and biochemical analyses. Immunofluorescence and electrophoretic analyses of the isolated bands reveal 14 components, among which tubulin, actin, myosin and a 90K glycoprotein were identified. Tannic acid-glutaraldehyde fixation reveals a conspicuous opaque material surrounding the microtubules. Cationized ferritin binding suggests the presence of anionic sites. Moreover, neuraminidase causes the disorganization of the microtubule-associated opaque material. The 90K glycoprotein is presumed to be related to the unusual stability of the microtubular system forming the marginal band.
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PMID:Observations on the molecular components stabilizing the microtubular system of the marginal band in the newt erythrocyte. 676 28

Anionic sites of rat epididymal spermatozoa were measured at pH 7.4 using tritiated polycationized ferritin. The spermatozoa from the caput region had 1.25 +/- 0.06 X 10(6) anionic sites per cell and a binding constant of 1.26 +/- 0.01 X 10(6) M-1. Spermatozoa from the cauda region had 1.50 +/- 0.09 X 10(6) anionic sites per cell and a binding constant of 4.84 +/- 0.82 X 10(6) M-1. The values were mean +/- s.d. The anionic sites were partly sensitive to treatments with neuraminidase, trypsin and Triton X-100.
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PMID:Measurement of anionic sites of rat epididymal spermatozoa using tritiated polycationized ferritin. 688 40

Changes in the permeability of the glomerular capillary wall (GCW) to native ferritin (NF), following detachment of the visceral epithelium from the glomerular basement membrane (GBM) were investigated. Detachment was induced by either perfusing kidneys with highly purified neuraminidase or by the induction of nephrosis through administration of puromycin aminonucleoside (PAN). Both experimental treatments resulted in marked glomerular ultrastructural changes which were characterized by focal detachment of the visceral epithelium from the GBM, replacement of the normal pattern of interdigitating foot processes with flattened expanses of continuous epithelium at certain areas of the GCW, and a generalized loss of sialic acid-rich epithelial cell cost in areas where the epithelium was detached as well as where it remained adherent. These changes were more frequent and prominent in the paramesangial regions of the glomeruli. When experimentally treated kidneys were perfused with NF, the tracer leaked into the urinary spaces in those areas of the GBM where the epithelium was detached. By contrast, in those areas of the GCW where the epithelium remained adherent, the tracer localized within the GBM mainly at the level of the lamina rara interna (LRI), and none of it appeared in the urinary spaces. Nephrotic and neuraminidase control kidneys were ultrastructurally normal, NF localizing mainly in the inner layers of the GBM. These data are consistent with the idea that the firm attachment of the epithelial foot processes to the GBM plays a vital role in determining the permselectivity properties of the GCW to plasma macromolecules.
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PMID:Altered glomerular permeability as a result of focal detachment of the visceral epithelium. 709 74

The surface charge of eosinophils, isolated from the peritoneal exudate of rats by the use of a Metrizamide gradient, was analysed by ultrastructural cytochemistry and cellular electrophoretic mobility. Binding of colloidal iron hydroxide and of cationized ferritin particles at pH 1.8 and 7.2 respectively, was observed on the surface of the eosinophils. An electrophoretic mobility of -1.08 and -1.39 micrometer.s-1.V-1.cm was determined for living and glutaraldehyde-fixed eosinophils, respectively. Treatment of the cells with neuraminidase reduced the electrophoretic mobility to -0.64 micrometer.s-1.V-1.cm (glutaraldehyde-fixed), reduced significantly and abolished completely the binding of both colloidal iron hydroxide and cationized ferritin particles to the surface of the cells. These results indicate that sialic acid exists on the surface of eosinophils, where it accounts for part of the negative surface charge.
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PMID:Surface charge of eosinophils. Binding of cationic particles and measurement of cellular electrophoretic mobility. 710 31


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