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

A simple post-embedding technique for the electron microscopical detection of lectin-binding sites using thin sections of tissues embedded in the resin LR White is described. With this technique, no prior etching of the sections is necessary. The cellular fine structure is well preserved and permits close correlation of the labelling to distinct cellular compartments. After mild aldehyde fixation (4% formaldehyde and 0.5% glutaraldehyde for 30 min), enterocyte brush border, vesicles and lysosomes as well as goblet cell Golgi apparatus and mucin are intensely stained after 30-60 min. The hydrophilia and penetrability of LR White is shown by the formation of oxidized diaminobenzidine reaction product arising from horseradish peroxidase-conjugated lectins. The precipitate not only covers the surface of the sections but is also formed within the resin, as is revealed on cross-sections through thin and semithin sections. The addition of 0.2 M solutions of the appropriate inhibitory sugars prevented staining, which indicates a specific binding. Examples are given of the binding of gold-, ferritin- and peroxidase-conjugated lectins for the purpose of detecting glycoconjugates in various intracellular compartments.
 ...
PMID:Post-embedding localization of glycoconjugates by means of lectins on thin sections of tissues embedded in LR white. 242 41

The morphologic display of testicular cancer is a heterogenous cellular pattern. A biological heterogeneity is also true for the expression of tumor markers. The biosynthesis of tumor marker proteins alpha-fetoprotein (AFP), ferritin, Schwangerschaftsprotein (SP 1) glycoprotein, tissue polypeptide antigen and of hormones (beta-human chorionic gonadotropin (HCG) = significantly present in nonseminoma germ cell tumors--does, however, define only a small number of cancer cells. To better visualize the majority of cancer cells, lectin binding was studied. During the oncogenic transformation a distinct change of cell membrane glycoproteins has been observed. Reactions of WGA/PNA lectins which get attached to glycoproteins with cancer tissue sample from seminomas (n = 20) and nonseminomas (n = 20) were analyzed. The results were correlated to AFP/beta-HCG positive (negative) immunohistology to establish further subgroups of biological homogeneity. The binding of WGA lectin appears relatively more frequent in both seminoma and nonseminoma than that of PNA. Lectin binding of WGA and/or PNA can be stained in 3/11 AFP- and beta-HCG-negative nonseminoma tissues while lectin staining is positive in 7/18 beta-HCG-negative seminomas. The fact that lectin binding is dependent on the spermatozoogenesis and on androgens in normal testis tissues asks for more detailed studies in this field.
 ...
PMID:[Lectin binding in immunohistologically AFP/HCG positive and negative testicular carcinoma]. 243 37

In the dystrophic Royal College of Surgeons (RCS) rat, migration of vessels from the inner retina into the retinal pigment epithelium (RPE) is associated with neovascular proliferation and formation of vitreo-retinal membranes (VRMs), (Caldwell et al., 1988; Frank and Das, 1988). We studied permeability and luminal membrane glycoconjugates in these vessels using horseradish peroxidase (HRP) and lectin-ferritin (Fe) techniques. RCS and genetic control rats were injected with HRP, their retinas were fixed, incubated in Fe conjugates of wheat germ agglutinin (WGA-Fe) or concanavalin-A (ConA-Fe), reacted to demonstrate HRP, and prepared for electron microscopy. The RPE and VRM vessels in RCS retinas were compared with the normal inner retina and choriocapillaris vessels in RCS and genetic control rats. In both groups inner retinal vessels formed a barrier to HRP, while fenestrated choriocapillaris (CE) vessels were permeable to the tracer. In both of these vascular beds plasma membrane WGA-Fe binding was dense and uniform, while ConA-Fe binding was sparse and patchy. Studies with competitive sugars showed that WGA-Fe binding was primarily to N-acetylglucosamine (NAG) and that ConA-Fe was to mannose. In both RPE and VRM vessels tight junctions appeared intact, but both vessel types were permeable to HRP with the RPE vessels often containing fenestrae and channels. As compared with binding in the inner retina and CE vessels, WGA-Fe binding was lower in VRM vessels and normal in RPE vessels, while ConA-Fe binding was higher in both RPE and VRM vessels. Thus, increased permeability is accompanied by alterations in both NAG and mannose residues in the VRM vessels and with alterations in mannose residues and the presence of fenestrations and channels in the RPE vessels.
 ...
PMID:Alterations in lectin binding accompany increased permeability in the dystrophic rat model for proliferative retinopathy. 260 72

We previously reported, in the spontaneously diabetic Bio-Breeding (BB) rat, an increase in horseradish peroxidase (HRP) uptake that was associated with reduction and patching of cationized ferritin (CF) binding to anionic sites on the luminal plasma membrane of the retinal capillary endothelium. To see whether alterations in the negatively charged terminal sugar residues, N-acetyl-glucosamine (NAG) and sialic acid (SA), might contribute to these changes in the diabetic rat retina, we used lectin-ferritin (Fe) conjugates to study the distribution of these sugars on the retinal endothelial luminal membranes. Wheat germ agglutin (WGA, binds to NAG and SA) and Limax flavius (LFA, binds only SA) were used. Plasma membrane WGA-Fe binding was dense and uniform in control animals. Binding sites were also found in coated luminal vesicles, within some uncoated luminal vesicles and on their diaphragms. Unlabeled uncoated luminal vesicles were also seen, suggesting two populations of uncoated vesicles. In diabetic animals, the binding sites were present within the same membrane associated microdomains as in the controls. However, in the majority of outer plexiform layer (OPL) vessels in diabetic animals, WGA-Fe binding was reduced to a single, discontinuous layer of particles (p less than 0.02). In both diabetic and control vessels, WGA-Fe binding was greatly reduced by the addition of competitive sugars. A few particles remained on the plasma membrane, on the diaphragms of some vesicles, and at the edge of vesicles. LFA-Fe binding was similar to that seen with WGA-Fe in the presence of competitive sugars. These results suggest that luminal membranes of retinal capillaries are rich in NAG and contain little SA. The sparse WGA-Fe binding pattern in the diabetic OPL may reflect decreases in number or accessibility of NAG residues, since similar binding patterns are seen in both the control and diabetic animals under conditions specific for SA. Thus, alteration of terminal NAG residues may contribute to decreased luminal surface anionic sites and increased pinocytotic transport in the retinal microvasculature of spontaneously diabetic BB rats.
 ...
PMID:Lectin-ferritin binding on spontaneously diabetic and control rat retinal microvasculature. 270 43

The plant lectin concanavalin A (con A) causes malformations of rabbit embryos when 160 micrograms (in 40 microliter) are injected into the exocoelom on gestational days 12-15 but does not cause malformations on days 10-11. The purpose of this study was to investigate the mechanism for increased susceptibility of day 12-15 embryos to con A teratogenicity. Light microscopy of day 11 embryos 15-20 hr after treatment with con A revealed no observable difference from controls. Day 13 embryos at similar times exhibited limb buds with large areas that were denuded of ectoderm. Concurrent addition of alpha-methyl-D-mannoside (alpha MM), a specific inhibitor of con A, to the injection solution of day 13 embryos resulted in limb buds that appeared normal. The regions of con A binding to day 11 and day 13 embryos were visualized through epifluorescent microscopy of untreated embryos stained with fluorescein-labelled con A. Day 11 embryos exhibited moderate fluorescence on the surface of limb buds and the pericardial region. Day 13 embryos exhibited strong fluorescence of limb bud surfaces; the pericardial region remained moderately fluorescent. Addition of alpha MM to the incubation medium resulted in no fluorescence above background. Visualization of con A receptors was accomplished by ultrastructural analysis of forelimb buds stained with ferritin-labelled con A. Ferritin label was observed only on the surfaces of the ectoderm and was sparse over all regions of day 11 limb buds. In contrast, ferritin label was moderately heavy in all regions of the day 13 limb buds. No labelling occurred when the ferritin-labelled con A was preincubated with alpha MM. These observations indicate that the number of exposed con A receptors on limb buds of teratogenically sensitive embryos (day 13) is increased, compared with the number of exposed receptors on limb buds of younger, insensitive (day 11) embryos. The increased number of exposed con A receptors on limb buds during the teratogenically sensitive period provides not only increased binding of the lectin to sensitive embryos but also a potential mechanism for the anomalous attachment of distal regions of the limb buds to the body wall.
 ...
PMID:Lectin teratogenesis. II: Demonstration of increased binding of concanavalin A to limb buds of rabbit embryos during the teratogenically sensitive period. 274 82

We have shown that a conjugate of wheat germ agglutinin (WGA), with horseradish peroxidase (HRP), is more sensitive than native HRP as a probe of neuroanatomic connections involving the retrograde transport of the lectin. It has also been shown in our laboratory that WGA-HRP remains at the site of injection twice as long as HRP. The purpose of the present morphometric study was to investigate the basis for the higher sensitivity of WGA-HRP over HRP as a retrogradely transported tracer molecule. To do this, we modified the experiment of Heuser and Reese which utilized the tracing of HRP in the frog neuromuscular junction (Heuser, J.E. and Reese, T.S., J. Cell Biol., 57 (1973) 315-344). Instead of using HRP alone, we examined, in double labeling experiments, fluid and adsorptive endocytosis with free HRP and WGA coupled to ferritin (WGA-ferritin) respectively. Immediately after nerve stimulation, both markers are taken up simultaneously into cisternae, and in tubular structures strikingly similar to the described compartment of uncoupling of receptor from ligand (CURL). Frequently, cisternae were connected with putative CURL. This early double labeling of cisternae and putative CURL was followed by the appearance of synaptic vesicles labeled with WGA-ferritin only (72-79%), HRP only (6-11%), and both labels (13-16%). In contrast to the labeling pattern of synaptic vesicles, the majority of cisternae and putative CURL had both labels throughout the duration of the experiments (77-80%). The results of this study indicate that most of WGA-ferritin and HRP are co-localized in cisternae and putative CURL, compartments involved in endocytosis and surface receptor recycling.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:A hypothesis for the superior sensitivity of wheat germ agglutinin as a neuroanatomical probe. 278 87

The distributions of electric charges and Concanavalin A binding sites in autophagic vacuoles and lysosomes in mouse hepatocytes were studied by utilizing a frozen ultrathin section labeling method with cationized ferritin (CF) or anionized ferritin and ferritin-conjugated Concanavalin A (Con A-F) as visual probes. Our observations revealed that the inner surface of the autophagic vacuole membrane has more anionic sites (CF binding) than other organelle membranes. This suggests that if the limiting membranes of autophagic vacuoles originate from preexisting membranes, such membranes must undergo structural and compositional alternation during the formation of the autophagic vacuoles. In contrast to CF, Con A-F showed no distinct binding to the membranes of autophagic vacuoles, but the contents of vacuoles displayed varying Con A-F binding, depending on the stage of the autophagic process. Increased binding was seen in more mature autophagic vacuoles. Since lysosomes showed a preferential accumulation of Con A-F particles, molecules with Con A-F binding sites in autophagic vacuoles may be of lysosomal origin. Con A-F distribution varied from lysosome to lysosome in the same cell, indicating heterogeneity of lysosomal contents. These results suggest that ferritin-conjugated lectin labeling methods applied to frozen, ultrathin section are a useful new approach in analyzing the natural history of autophagic vacuoles and the heterogeneity of lysosomes.
 ...
PMID:Distribution of electric charges and concanavalin A binding sites on autophagic vacuoles and lysosomes in mouse hepatocytes. 280 5

Mutants of Actinomyces viscosus T14V lacking type 1 or type 2 fimbriae or both were selected by their failure to react with rabbit antibodies against either or both fimbrial antigens. Immunospecific double labeling with iron dextran and ferritin-conjugated antibodies showed two types of fimbriae on individual cells of the parent organism, a single type on mutant strains with type 1+2- and type 1-2+ fimbriae and no labeled or unlabeled fimbriae on a type 1-2- fimbria-deficient strain. The mutational loss of one fimbrial antigen did not appear to affect expression of the other, since bacteria with one or two types of fimbriae bound similar amounts of a monoclonal antibody directed against the fimbrial antigen present on both bacterial phenotypes. The strong adsorption of strains with type 1+2+ or 1+2- fimbriae to saliva-treated hydroxyapatite and weak adsorption of those with type 1-2+ or no fimbriae was consistent with the known involvement of type 1 fimbriae in this attachment process. Similarly, the A. viscosus lectin was clearly associated with the expression of type 2 fimbriae, since only the strains with type 1+2+ or 1-2+ fimbriae participated in lactose-sensitive coaggregations with Streptococcus sanguis 34. Further studies using the fimbria-deficient mutant strains showed that aggregation of A. viscosus T14V in the presence of sialidase-treated human saliva involved both types of fimbriae, whereas neither type was required for the lactose-resistant coaggregation of the organism with certain streptococcal strains.
 ...
PMID:Mutants of Actinomyces viscosus T14V lacking type 1, type 2, or both types of fimbriae. 290 12

Mannose-binding sites were detected at the ultrastructural level in nuclei of lizard granulosa cells in situ by means of mannosylated ferritin. When ultrathin sections of material embedded in glycol methacrylate were incubated with mannosylated ferritin, a strong labelling was observed over nucleoli, chromatin and the external leaflet of the nuclear envelope, but no labelling was detected in the perinuclear space except for nuclear pores. This labelling was clearly inhibited when sections were incubated in a solution containing both mannosylated ferritin and a sugar-related neoglycoprotein (mannosylated serum albumin). These ultrastructural data supporting the existence of nuclear lectin-like components in reptilian cells are in agreement with our previous findings about such components in nuclei isolated from mammalian cells. Owing to the unique organization of the granular component of the nucleoli in specialized granulosa cells, we are able to show that some of the mannose-binding sites are associated with ribosomal precursors.
 ...
PMID:In situ ultrastructural localization of sugar-binding sites in lizard granulosa cell nuclei. 293 91

The nature and distribution of some carbohydrate receptors on the cell membrane of transformed human B- and T-derived lymphocyte cell lines (RPMI-1788, Daudi, Jurkat, Molt-4) are studied by Ricinus communis agglutinin, soybean agglutinin, Helix pomatia lectin, peanut agglutinin and wheat germ agglutinin conjugated with ferritin and colloidal gold. The quality of receptors and the manner of their distribution detected by different lectins are considerably different.
 ...
PMID:[Cell surface receptors in lymphoid lines studied using lectins]. 302 7


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>