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

The expression of IgG receptor sites at the band 3 protein is important for the recognition and elimination of aged and experimentally altered erythrocytes. Membrane bound IgG was detected in different erythrocyte preparations and microvesicles by means of electron microscopic procedures (protein A-gold-, protein A-gold-silver- and anti-ferritin-sandwich-technique) and light microscopic procedures (immunofluorescence). Physiologically "old", pronase and neuraminidase as well as diamide treated erythrocytes and microvesicles demonstrated significant IgG loading. An increased IgG binding of erythrocytes treated with phenylhydrazine was only evident when higher phenylhydrazine concentrations were used. Both, the alteration of the glycocalyx (conformational changes of the external segment of the glycophorins) and the alteration of the membrane skeleton lead to an unmasking of the IgG receptor site at band 3 proteins (transmembrane effect). The result is an overcritical loading of cells with IgG molecules which initiate the elimination of the erythrocytes by macrophages of the Reticulo-Histiocytic-System.
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PMID:[Immunocytochemical determination of membrane-bound IgG using physiologically aged and experimentally aged erythrocytes]. 248 13

The effects of propranolol (10(-3) mM) on the surface anionic groups of Herpetomonas muscarum muscarum were analysed by cell electrophoresis, by ultrastructural cytochemistry and by identification of sialic acids using paper chromatography. Differentiation of H. muscarum muscarum induced by propranolol treatment caused a significant increase in the net negative surface charge. Binding of cationized ferritin (CF) and colloidal iron hydroxide particles was observed at the cell surface of both untreated and propranolol-treated cells. In cells incubated in the presence of the drug the CF particles were distributed in all membrane regions. However, there were small areas where the particles were absent. In H. muscarum muscarum exposed to propranolol the density of residues of sialic acid per cell was higher, and the agglutinating activity with Sendai virus was more intense. However, the pattern of sialic acid, characterized by the presence of N-acetylneuraminic acid derivative, was not modified upon cell interaction with the drug. Treatment of both control and propranolol-treated protozoa with neuraminidase significantly reduced the surface charge. These findings suggest that sialic acid residues are the major anionogenic groups exposed on the surface of H. muscarum muscarum.
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PMID:Changes in cell surface anionogenic groups induced by propranolol in Herpetomonas muscarum muscarum. 254 16

To study components of anionic sites on the lamina densa of the dermo-epidermal junction (DEJ) and to assess the effect of removal of sialic acid or glycosaminoglycans on its charge-selective permeability, epidermal sheets, whose dermis had been removed by treatment with dithiothreitol, were digested with heparitinase, chondroitinase ABC, hyaluronidase, or neuraminidase. They were then stained with polyethyleneimine for demonstration of the anionic sites or incubated in a medium containing native anionic ferritin for tracer experiments. The anionic sites were completely removed after heparitinase digestion. Although the numerical density of the sites was not altered, their electron density was decreased after chondroitinase ABC digestion. The other enzymes had no effect on the sites. In the tracer experiments, heparitinase or neuraminidase increased the number of tracer molecules penetrating into the lamina lucida of the epidermal sheet, while the other enzymes had no effect on it. These data indicate that heparan sulfate, which is a main component of the anionic sites, plays an important role in the charge-selective permeability of the DEJ, whereas chondroitin sulfate, which seems to be contained in the sites, does not, probably because of its small amount. These data also indicate that sialic acid, which is not a main component of the anionic sites demonstrated with the cationic probe, has a role in the permeability function.
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PMID:Effect of enzyme digestion on anionic sites and charge-selective permeability of dermo-epidermal junction. 258 48

The surface anionic groups of Entamoeba invadens were analysed by cell electrophoresis, by ultrastructural cytochemistry, and by identification of sialic acids using paper and gas-liquid chromatography. Binding of colloidal iron hydroxide (CIH) and of cationized ferritin (CF) particles at pH 1.8 and 7.2, respectively, was observed on the cell surface. E. invadens has a highly negative surface charge (-0.96 microns s-1 V-1 cm). Treatment of the cells with trypsin and neuraminidase significantly reduced the electrophoretic mobility by 24% and 40%, respectively. Treatment of the amoebae with neuraminidase also markedly decreased the binding of CIH to the cell surface. This finding suggests that sialic acid residues are the major anionogenic groups exposed on the surface of E. invadens. Paper and gas-liquid chromatography showed that N-acetylneuraminic acid was the only derivative characterized in E. invadens.
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PMID:Sialic acid is a cell surface component of Entamoeba invadens trophozoites. 273 83

The presence, distribution and content of sialic acid on the cell surface in collagenase-dispersed acini obtained both from unstimulated as well as from in vivo isoproterenol-stimulated mouse parotid have been studied. To this end, sialic acid residues have been qualitatively and quantitatively analyzed by 1) cytochemical labeling by wheat germ agglutinin (WGA), 2) biochemical procedures and 3) isotopic labeling by [3H]WGA (WGA-N-[acetyl-3H]-acetylated). Electron microscopy revealed striking differences in the binding of ferritin-conjugated WGA at the basal, lateral and apical cell surface. Unstimulated acinar cells showed a heavy patch-distributed binding of ferritin-conjugate on the basal cell surface while it was homogeneous and very scarce on the lateral one and absent on the apical cell surface. During the first few hours after isoproterenol, the WGA binding sites at the basal cell surface became homogeneously distributed. This fact was coincident with a loss of about 60 to 70% both in the content of neuraminidase-releasable sialic acid and in the binding of [3H]WGA to the acinar surface. These findings suggest that the release of sialic acid as free residues, which has been involved in the isoproterenol-triggered cell proliferation-inducing mechanism in the mouse parotid, would occur at the glycocalyx corresponding to the basal plasma membrane of the acinar cells.
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PMID:Changes in the content and distribution of sialic acid on the basal surface of isoproterenol-stimulated mouse parotid acinar cells. 275

Erythrocyte surface membrane sialyl residues were investigated by means of affinity cytochemistry using the avidin-biotin complex technique. Mild oxidation with the periodate (MO)-biotin hydrazide (BHZ)-ferritin avidin conjugate (FAv) sequence revealed numerous ferritin particles on erythrocytes from healthy donors. The ferritin particles attached on the perpendicularly sectioned membrane were seen at an average distance of 10 to 12 nm from the outer dense leaflet of the cell membrane. Pretreatment with neuraminidase followed by the MO-BHZ-FAv sequence almost eliminated erythrocyte ferritin labeling. Erythrocytes from diabetic patients showed less dense ferritin labeling compared with those from healthy donors. Quantiative analysis of sialyl residues demonstrated a marked reduction in ferritin labeling of erythrocytes from diabetic patients which was significantly less (p less than 0.01) than that of erythrocytes from healthy donors. This observation supports previous biochemical data demonstrating lower levels of surface membrane negative charge and sialyl residues on erythrocytes from patients with diabetes mellitus.
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PMID:Qualitative and quantitative analysis of erythrocyte surface membrane sialyl residues using affinity cytochemistry with special reference to diabetic patients. 286 31

The location and chemical composition of anionic sites on the endothelium of the choriocapillaris was investigated with cationic ferritin and enzyme digestion techniques. Cationic ferritin administered intravenously initially labeled essentially all fenestral diaphragms. Within 30 min after injection, no diaphragms remained labeled, but they could be relabeled by a second cationic ferritin injection. Following perfusion of cationic ferritin, the entire luminal front of the endothelium was labeled: the plasmalemma and fenestral, vesicle, and channel diaphragms. Perfusion of neuraminidase or chondroitinase did not affect subsequent cationic ferritin binding. In contrast, heparitinase removed anionic sites on all structures except fenestral diaphragms. Cationic ferritin did not mark the endothelium following heparinase digestion. All sites were cleaved with pronase E. These results indicate that heparin is the anionic moiety on fenestral diaphragms while the glycocalices of the plasmalemma and vesicle and channel diaphragms are rich in a heparan sulfate proteoglycan. Furthermore, since the heparan sulfate localized to these structures was digested by both heparinase and heparitinase, it is in a form similar to heparin. These findings demonstrate that the endothelium of the choriocapillaris bears cell-surface anionic components that are different than those described for fenestrated endothelia lining other vascular beds.
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PMID:The cell surface of a restrictive fenestrated endothelium. II. Dynamics of cationic ferritin binding and the identification of heparin and heparan sulfate domains on the choriocapillaris. 293 59

Polycationic labels such as cationized ferritin and colloidal iron were used to evaluate the surface negative charges over the mandibular condyles of ICR mice. The effects of neuraminidase, hyaluronidase, pronase, and collagenase on the binding of cationized ferritin and colloidal iron particles to the condylar articular surface were also studied. The results of this study clearly indicate that the surface area of the cartilaginous condyle is negatively charged and that its composition consists mainly of a collagenous material embedded within a proteinaceous matrix. With age, a substantial decrease in the density of negative charges took place along the surface area and, in particular, in the context of sialic acid residues. It is, therefore, possible that the reduction in cartilage surface charge might be associated with the onset of osteoarthritic changes commonly seen in aging humans and experimental animals.
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PMID:Cartilage surface charge. A possible determinant in aging and osteoarthritic processes. 298 74

We have investigated the site of surface expression of the neuraminidase (NA) glycoprotein of influenza A virus, which, in contrast to the hemagglutinin, is bound to membranes by hydrophobic residues near the NH2-terminus. Madin-Darby canine kidney or primary African green monkey kidney cells infected with influenza A/WSN/33 virus and subsequently labeled with monoclonal antibody to the NA and then with a colloidal gold- or ferritin-conjugated second antibody exhibited specific labeling of apical surfaces. Using simian virus 40 late expression vectors, we also studied the surface expression of the complete NA gene (SNC) and a truncated NA gene (SN10) in either primary or a polarized continuous line (MA104) of African green monkey kidney cells. The polypeptides encoded by the cloned NA cDNAs were expressed on the surface of both cell types. Analysis of [3H]mannose-labeled polypeptides from recombinant virus-infected MA104 cells showed that the products of cloned NA cDNA comigrated with glycosylated NA from influenza virus-infected cells. Both the complete and the truncated glycoproteins were found to be preferentially expressed on apical plasma membranes, as detected by immunogold labeling. These results indicate that the NA polypeptide contains structural features capable of directing the transport of the protein to apical cell surfaces and the first 10 amino-terminal residues of the NA polypeptide are not involved in this process.
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PMID:Surface expression of influenza virus neuraminidase, an amino-terminally anchored viral membrane glycoprotein, in polarized epithelial cells. 301 20

Polycationic derivatives of ferritin containing primary amino groups (CFah) or tertiary amino groups (CFdmp) were potent platelet agonists inducing shape change, aggregation and secretion, but also agglutination in the presence of EDTA. Pretreatment of platelets with neuraminidase, PGE1, indomethacin, or creatine kinase/creatine phosphate inhibited CF-induced activation. In contrast, neuraminidase and PGE1 increased the agglutination by CF, indicating an inverse relationship between activation and CF-induced agglutination. At pH 7.4, the cationic charges of CFdmp exceeded those of CFah by a factor of 1.5 and the platelets bound approximately 1.5 times more CFah than CFdmp, suggesting the same number of anionic surface sites for both CF preparations. The capacity of the platelets to bind CF was diminished by 55% at 0 degree C or by 62% after aldehyde fixation and by 13% with PGE1. This suggests that the binding capacity depends on the mobility of the binding sites in the plane of the membrane but is only slightly increased by platelet activation. Binding to fixed or cold platelets approached equilibrium within a few seconds whereas saturation required several minutes at 37 degrees C. Neuraminidase preferentially reduced the slow binding and much less the rapid binding. Since activation by CF developed during seconds, suppressible by a brief treatment with neuraminidase 25 mU/ml, a small portion of neuraminidase-sensitive sites appears to be necessary for CF-induced platelet activation. Full activation and agglutination occurred at CF concentrations far below saturating concentrations. The results show that neither CF-induced activation nor agglutination depend on a simple neutralization of the negative surface charge.
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PMID:Cationized ferritin as a platelet-stimulating surface probe. Binding to platelets and effects on platelet function. 308 60


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