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)

Although the basic biochemical defect in cystic fibrosis (CF) is unknown, previous studies have indicated that errors in protein glycosylation may be involved in the pathogenesis of the disease. Utilizing human skin fibroblasts, the present study was designed to quantitatively analyze glycosylation of cell surface glycoconjugates in CF and normal cells. Cell surface glycoconjugates were analyzed using 125I-concanavilin A (Con A), 125I-WGA, and Con A-ferritin conjugates. Under our binding conditions, Con A was used as a probe for mannose residues and WGA was used as a probe for N-acetylglucosamine residues. Saturable binding of both probes was observed and appropriate sugar controls confirmed the specificity of each lectin. When compared on a DNA basis, iodinated lectin binding studies indicated that no consistent differences existed between CF and normal strains of human skin fibroblasts. Ultrastructural quantitative morphometric analysis of Con A-ferritin conjugate binding indicated that neither proteolysis of cell surface glycoconjugates or internalization of lectin probes was occurring at saturable binding concentrations. In summary, our results indicated that no consistent differences in cell surface mannose and N-acetylglucosamine residues could be detected between the normal and CF strains of human skin fibroblasts used in these studies.
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PMID:Analysis of cell surface glycoconjugates in fibroblasts from patients with cystic fibrosis. 337 Aug 43

Glycoconjugates, including glycolipids, glycoproteins, and proteoglycans, are present in the plasma membrane of photoreceptor cells and in the interphotoreceptor matrix surrounding photoreceptor cell ellipsoids and outer segments. Although the precise function of these molecules is unknown, they may be important in mediating photoreceptor-pigment epithelial cell interactions, outer segment membrane assembly, and/or disc shedding. Lectins, affinity ligands for defined carbohydrate sequences, have proven particularly useful in studying the glycoconjugate composition of the interphotoreceptor matrix. The peanut lectin selectively binds to domains of the interphotoreceptor matrix surrounding cone ("cone matrix sheaths"), but not rod inner and outer segments. This is evidence for the existence of chemical and structural heterogeneity within the interphotoreceptor matrix. The studies described herein utilized ultrastructural pre-embedding histochemical labeling to assess whether, in addition to the surrounding interphotoreceptor matrix, peanut lectin binding is associated directly with that plasma membrane of cone inner and outer segments. This study confirms that ferritin-conjugated peanut agglutinin binds to cone matrix sheaths, and, in addition, provides ultrastructural evidence for the presence of binding to the plasma membrane surrounding cone inner and outer segments. The data suggest that cone membrane-associated peanut agglutinin-binding molecules may differ from those located within cone matrix sheaths.
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PMID:Ultrastructural visualization of primate cone photoreceptor matrix sheaths. 337 60

The binding sites of two lectins, peanut agglutinin (PNA) and wheat germ agglutinin (WGA), in the interphotoreceptor matrix (IPM) and photoreceptor plasma membranes of the Japanese monkey (Macaca fuscata) retina were localized using a pre-embedding staining method with ferritin-conjugated (Fer) lectins as well as a postembedding staining method with fluorescence-labeled (FITC) lectins. FITC-PNA, but not WGA, stained cylindrical domains of the IPM around cone outer and inner segments, while the IPM around rods stained with FITC-WGA but not PNA. When the intact (not detached) retinal tissues were incubated with Fer-lectin, the lectin generally labeled neither the IPM nor photoreceptor plasma membranes, but labeled only those structures in detached portions occurring at the edges of occasional retinal tissue blocks. Thus, the neural retinas physically isolated from the retinal pigment epithelium (RPE) were utilized principally here. Ultrastructurally, the IPM in the intact retina consisted of granular and filamentous materials; the IPM in the isolated neutral retina also retained those components, although somewhat loosely organized, and the IPM around cones appeared to be preserved better than did the IPM around rods. Fer-PNA bound to the IPM associated with cones, but not rods; Fer-WGA bound to the rod- but not cone-associated IPM. The ferritin particles were found to lie close to the granular and filamentous materials. Those photoreceptor-associated IPMs extended to the apical surface of the RPE in detached portions or to the apical villi of the RPE which were frequently found in the isolated neural retinas. Also, Fer-PNA labeled the cone, but not rod, plasma membranes; Fer-WGA bound heavily to the plasma membranes of rod and cone outer segments, but sparsely to those of their inner segments. These results suggest that the IPM comprises chemically and physically differential domains specialized for cone and rod photoreceptor cells, and that these specialized IPM are structurally so stable that may be involved in isolating photoreceptor cells physicochemically from each other and in the interactions between the photoreceptors and the RPE, such as retinal adhesion.
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PMID:Specialization of the interphotoreceptor matrices around cone and rod photoreceptor cells in the monkey retina, as revealed by lectin cytochemistry. 342 1

When the sperm of the toad Bufo japonicus were treated with fluorescein isothiocyanate (FITC)-conjugated peanut agglutinin (PNA), soybean agglutinin (SBA), or Dolichos biflorus agglutinin (DBA), a few sperm fluoresced at the acrosomal region. The number of sperm showing this lectin binding to the acrosome increased significantly upon mild sonication of the sperm suspension. Electron microscopy revealed that ferritin-conjugated PNA bind not to the outer acrosomal and overlying plasma membranes, but specifically to the surface of the inner acrosomal membrane exposed by sonication. Both the percentage of FITC-PNA-labeled sperm and the activity of vitelline coat lysin released by sperm increased in good correlation with increasing sonication time, although the PNA-labeled sperm decreased in number upon longer sonication. These results indicate that the binding of FITC-PNA to the sperm provides a reliable measure of the acrosome reaction of Bufo sperm.
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PMID:Detection of acrosome-reacted toad sperm based on specific lectin binding to the inner acrosomal membrane. 350 73

The distribution of anionic residues on the surface of erythrocytes infected with Plasmodium falciparum was studied using cationized ferritin (CF) and transmission electron microscopy. CF staining of uninfected erythrocytes or erythrocytes infected with a knobless variant resulted in a dense and uniform distribution of ferritin particles; however, when red cells infected with a knob-inducing variant were exposed to CF, aggregates of ferritin particles were observed in the region of membrane elevation. Lectin binding to the erythrocyte surface was visualized by transmission electron microscopy using ferritin-conjugated lectins and lectin-fetuin-gold. No differences were observed in the lectin-binding patterns of malaria-infected or uninfected erythrocytes using WGA (wheat-germ agglutinin), RCA (ricin), and Limax flavus lectin. In distinct contrast to the uniform distribution of ferritin particles seen with these lectins was the appearance of clusters of ferritin-ConA over the knobby regions. Localized aggregates of ConA were not seen in knob-free areas or on the surface of red cells infected with a knobless variant. No significant differences were found in the agglutination reactions of normal and infected cells with the Cancer antennarius lectin specific for O-acylated sialic acids.
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PMID:Plasmodium falciparum: regional differences in lectin and cationized ferritin binding to the surface of the malaria-infected human erythrocyte. 352 94

Terminal saccharide sequences in rat photoreceptor cell surface glycoconjugates were characterized. Lectin cytochemistry and electron microscopy were used for preembedding cytochemical localization of surface carbohydrates. Neuraminidase digestion was employed for the exposure of penultimate saccharides in sialoglycoconjugates. Isolated rat retinas were incubated with ferritin-labeled wheat germ agglutinin (WGA), peanut agglutinin (PNA), and soybean agglutinin (SBA) prior to and after neuraminidase digestion. PNA and SBA did not label untreated photoreceptors. WGA densely labeled the photoreceptor surface and interphotoreceptor matrix (IPM) components. Following neuraminidase treatment, PNA, but not SBA, labeled the photoreceptor surface and the IPM. WGA labeling of the IPM was abolished, and the labeling of the photoreceptor surface was reduced. Based on the lectin specificity, it was concluded that photoreceptor surface glycoconjugates in the rat retina contain a terminal trisaccharide: sialic acid-D-galactose-(beta 1----3)-N-acetyl-D-galactosamine.
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PMID:Cytochemical characterization of sialoglycoconjugates on rat photoreceptor cell surface. 355 69

M cells in Peyer's patch epithelium conduct transepithelial transport of luminal antigens to cells of the mucosal immune system. To determine the distribution of specific lectin-binding sites on luminal membranes of living M cells and to follow the transport route of membrane-bound molecules, lectin-ferritin conjugates and cationized ferritin were applied to rabbit Peyer's patch mucosa in vivo and in vitro. The degree to which binding enhances transport was estimated by comparing quantitatively the transport of an adherent probe, wheat germ agglutinin-ferritin, to that of a nonadherent BSA-colloidal gold probe. When applied to fixed tissue, the lectins tested bound equally well to M cells and columnar absorptive cells. On living mucosa, however, ferritin conjugates of wheat germ agglutinin and Ricinus communis agglutinins I and II bound more avidly to M cells. Absorptive cells conducted little uptake and no detectable transepithelial transport. Lectins on M cell membranes were endocytosed from coated pits, rapidly transported in a complex system of tubulocisternae and vesicles, and remained adherent to M cell basolateral membranes. Cationized ferritin adhered to anionic sites and was similarly transported, but was released as free clusters at M cell basolateral surfaces. When applied simultaneously to Peyer's patch mucosa, wheat germ agglutinin-ferritin was transported about 50 times more efficiently than was bovine serum albumin-colloidal gold.
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PMID:Transport of membrane-bound macromolecules by M cells in follicle-associated epithelium of rabbit Peyer's patch. 356

A method using low concentrations of formaldehyde and dithiothreitol was applied to obtain 'right-side out' luminal plasmalemma-derived vesicles from bovine aortic endothelial cells (EC) in culture, and from human umbilical vein and bovine or porcine aortas perfused ex vivo with the vesiculation solution. Vesicle formation and shedding were examined by phase-contrast microscopy and by transmission (TEM) and scanning electron microscopy (SEM). Vesicles showed the characteristic trilaminar pattern of the unit membrane and did not contain cellular organelles. As detected in freeze-fracture preparations, vesicle membrane displayed intramembrane particles and filipin-detectable cholesterol. Like EC plasmalemma, vesicle surface was heavily stained by Ruthenium Red and bound under a normal pattern cationized ferritin and ferritin hydrazide. As indicated by lectin agglutination assays and by ultrastructural cytochemistry, vesicles maintained on their ectodomains glycoconjugates bearing monosaccharides such as N-acetyl-neuraminic acid, beta-N-acetylglucosamine and beta-D-galactose, and expressed 5'-nucleotidase activity. The electrophoretic profiles of externally disposed 125I-labelled polypeptides of vesicles were found to be similar to those of intact EC. Chemically-induced vesiculation appears as a suitable method to obtain EC plasmalemma for studying its composition and functions in various vascular beds.
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PMID:Endothelial cell plasma membrane obtained by chemically induced vesiculation. 359 39

In order to study differences in cell-surface sugars which may be involved in the phagocytic defect in Royal College of Surgeons (RCS) retinas, we have examined the presence or absence of lectin binding to carbohydrates on retinal pigment epithelial (RPE) plasma membranes of dystrophic (RCS-p+) and normal (Long-Evans) rats. A lectin which binds to both sialic acid and N-acetylglucosamine sugar residues, wheat germ agglutinin-ferritin (WGA-fe), was used. The specificity of WGA-fe binding to each sugar was studied by either pre-treating the tissue with neuraminidase enzyme which removes sialic acid residues, or by incubating the WGA-fe lectin with one of the haptens, N-acetylglucosamine. In non-enzyme-treated tissue, RPE cell-surface membranes from RCS retinas were densely labeled with WGA-fe as compared with the labeling on normal RPE, which appeared less dense and patchy in distribution. Wheat germ agglutinin-ferritin labeling in the presence of N-acetylglucosamine was blocked on both RCS and normal RPE surface membranes. After pre-treatment with neuraminidase, WGA-fe labeling on dystrophic RPE membranes was similar to non-enzyme-treated tissue but was enhanced on normal RPE. Labeling was blocked when N-acetylglucosamine was present with the lectin after enzyme pre-treatment. Other lectins which specifically bind to sialic acid, Limulus polyphemus agglutinin-ferritin (LPA-fe) and Limax flavus agglutinin (LFA) demonstrated sparse or no labeling on both RCS and normal RPE membranes. Our data suggests that N-acetylglucosamine residues predominate on RCS and normal RPE cell-surface membranes and that sialic acid binding sites are either not accessible to the lectins or may not be present.
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PMID:Examination of sialic acid binding on dystrophic and normal retinal pigment epithelium. 359 57

Statistical procedures were used to estimate lectin receptor distribution on the surface of ascite lymphoma cells, neuroblastoma C-1300 cells and of transformed human T- and B-derived lymphoid cell lines. Relationships between the arithmetic means and mean square variances for sample populations from each cell and ferritin- or colloidal gold-lectin combination were used to define four types of topographical distributions: uniform-ordered, uniform-random, random and clustered.
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PMID:[Evaluation of the distribution of lectin receptors on the surface of tumor and transformed cells using methods of variation statistics]. 360 7


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