Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.11.1.7 (peroxidase)
65,474 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous investigations have shown that tetanus toxin is transported retrogradely in all peripheral neurons whereas the transport of NGF is confined to adrenergic and sensory neurons. Other macromolecules with molecular weights and general physiochemical properties similar to NGF and tetanus toxin (e.g., cytochrome C, insulin, horseradish peroxidase and bovine serum albumin) are not transported to a detectable extent if injected in comparable molar concentrations. For tetanus toxin, which is transported in all peripheral neurons, it has be assumed that it's retrograde transport depends on properties common to all neurons. In view of the relatively high ganglioside content of the neurons and the high affinity of tetanus toxin for the trisialoganglioside GT1, we studied the influence of gangliosides on the retrograde transport of tetanus toxin as compared to NGF. We included into the study cholera toxin which is known to have a high affinity for the monosialoganglioside GM1 and wheat germ agglutinatinin, a lectin with specific affinity for glycoproteins with N-acetyl-glucosamine residues. Both cholera toxin and wheat germ agglutinin were transported efficiently in all peripheral neurons. Preincubation of 125I-cholera toxin with monosialoganglioside GM1 completely blocked its retrograde axonal transport. The transport of NGF and wheat germ agglutinin was affected neither by various purified gangliosides nor by a mixture of bovine brain gangliosides. The transport of tetanus toxin was only reduced by 50% both by the trisialoganglioside GT1 and the bovine ganglioside mixture.
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PMID:Role of gangliosides in the uptake and retrograde axonal transport of cholera and tetanus toxin as compared to nerve growth factor and wheat germ agglutinin. 7 Feb 59

The fate of tetanus toxin (mol wt 150,000) subsequent to its retrograde axonal transport in peripheral sympathetic neurons of the rat was studied by both electron microscope autoradiography and cytochemistry using toxin-horseradish peroxidase (HRP) coupling products, and compared to that of nerve growth factor (NGF), cholera toxin, and the lectins wheat germ agglutinin (WGA), phytohaemagglutinin (PHA), and ricin. All these macromolecules are taken up by adrenergic nerve terminals and transported retrogradely in a selective, highly efficient manner. This selective uptake and transport is a consequence of the binding of these macromolecules to specific receptive sites on the nerve terminal membrane. All these ligands are transported in the axons within smooth vesicles, cisternae, and tubules. In the cell bodies these membrane compartments fuse and most of the transported macromolecules are finally incorporated into lysosomes. The cell nuclei, the parallel golgi cisternae, and the extracellular space always remain unlabeled. In case the tetanus toxin, however, a substantial fraction of the labeled material appears in presynaptic cholinergic nerve terminals which innervate the labeled ganglion cells. In these terminals tetanus toxin-HRP is localized in 500-1,000 A diam vesicles. In contrast, such a retrograde transsynaptic transfer is not at all or only very rarely detectable after retrograde transport of cholera toxin, NGF, WGA, PHA, or ricin. An atoxic fragment of the tetanus toxin, which contains the ganglioside-binding site, behaves like intact toxin. With all these macromolecules, the extracellular space and the glial cells in the ganglion remain unlabeled. We conclude that the selectivity of this transsynaptic transfer of tetanus toxin is due to a selective release of the toxin from the postsynaptic dendrites. This release is immediately followed by an uptake into the presynaptic terminals.
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PMID:Selective retrograde transsynaptic transfer of a protein, tetanus toxin, subsequent to its retrograde axonal transport. 9 75

An immunoelectron microscopic method is described for sensitive high-resolution visualization of tissuebound cholera toxin. The principle is to incubate cells or tissue sections with toxin and then to localize the bound toxin with toxin-specific peroxidase (donor:hydrogen-peroxide oxidoreductase; EC 1.11.1.7)-conjugated antibody and enzyme substrate. Thin sections are examined for electron-opaque precipitates in a transmission electron microscope. Because of the specific binding of the toxin to membrane ganglioside G(M1), the method can be used for ultrastructural localization of this ganglioside. Semiquantitative data are obtained by titration of the limiting concentration of cholera toxin producing specific precipitates. The specificity of the method was controlled in various ways, including analyses of the correlation between the immunoelectron microscopy results and determinations of ganglioside G(M1) in tissues with different ganglioside concentrations, tissues hydrolyzed with Vibrio cholerae sialidase, tissues in which exogenous G(M1) has been incorporated, and lipid-extracted tissues. The immunoelectron microscopic method demonstrates that membrane G(M1) ganglioside is positioned on the external side exclusively. Cell-bound toxin remains in its original location on the plasma membrane surface of cells below 18 degrees , but appears to be redistributed both laterally and vertically in the membrane of cells incubated at 37 degrees for 30 min or longer. The results of this method indicate that in the central nervous system G(M1) is concentrated in the pre- and postsynaptic membranes of the synaptic terminals; a further increase in reactivity of these structures after hydrolysis of the nervous tissue with V. cholerae sialidase suggests that higher gangliosides of the same series are particularly increased in the pre- and postsynaptic junctions.
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PMID:Ultrastructural localization of cell membrane GM1 ganglioside by cholera toxin. 26 32

Cholera toxin linked covalently by glutaraldehyde to horseradish peroxidase was incubated with cultured chicken sympathetic neurons at 4 degrees. Cells were washed and brought to 37 degrees to permit endocytosis of bound toxin on plasma membranes. Massive internalization of the ligand into vesicles and cisterns of the Golgi--endoplasmic reticulum--lysosome (GERL) system was demonstrated by the cytochemical reaction for the enzyme. Surface binding and subsequent endocytosis of the cholera toxin--enzyme conjugate was inhibited when conjugate and monosialoganglioside (GM1) were simultaneously applied to cells at 4 degrees. Cholera toxin is not toxic to neurons at the levels used. These results indicate that GERL is the primary site of endocytosis of presumed complexes of cholera toxin with its plasma membrane receptor (GM1 ganglioside-containing moieties). It is suggested that, in neurons, plasma-membrane bound ligands are taken up primarily into GERL.
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PMID:Endocytosis of cholera toxin into neuronal GERL. 27 52

125I-Labeled membrane glycoproteins that specifically interact with diphtheria toxin and CRM197 protein--but not with diphtheria toxoid, fragment A of diphtheria toxin, or cholera toxin--were detected by use of the lactoperoxidase labeling technique followed by an immunoprecipitation system. These glycoproteins, which adhere to lentil lectin-Sepharose columns, are present on the surface of diphtheria toxin-sensitive guinea pig lymph node cells but are completely lacking on the surface of diphtheria toxin-resistant mouse L cells. The major 125I-labeled glycoprotein that interacts with diphtheria toxin exhibits anomalous behavior, characteristic of glycoproteins, when analyzed by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. This demonstration of the biochemical nature of specific diphtheria toxin binding membrane components raises the possibility that the detected components are diphtheria toxin receptors.
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PMID:Immunoprecipitation and partial characterization of diphtheria toxin-binding glycoproteins from surface of guinea pig cells. 37 Aug 34

Methods for light and electron microscopic identification and characterization of intestinal cholera antitoxin-containing cells (ACC) using peroxidase-labeled immunoreagent are described and used to study the ACC response in mice after immunizations with cholera toxin. Specific ACC appeared in significant numbers after two oral immunizations and increased six- to eightfold with two additional oral boosters, whereas further oral immunizations caused no additional stimulation. Intravenous immunizations had to be repeated seven times before ACC could be detected. After two oral immunizations, most of the ACC were found in the proximal part of the small intestine and no ACC were seen in the colon. This uneven distribution of ACC within the small intestine was eliminated after four oral immunizations, when ACC could also be detected in the colon. The ACC response after four oral immunizations demonstrated a peak at 4 days with far fewer cells present at 2 and 7 days. Electron microscopic studies showed that the ACC were mature plasma cells with the staining localized to the endoplasmic reticulum. Regression analysis of the relationship between the number of ACC and the magnitude of protective immunity against intestinal challenge with cholera toxin indicates a highly significant correlation (r = 0.91, P less than 0.001).
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PMID:Local cholera immunity in mice: intestinal antitoxin-containing cells and their correlation with protective immunity. 45 57

Cholera toxin (CT), covalently attached to horseradish peroxidase (HRP), is a specific cytochemical marker for GM1 ganglioside (GM1) and retains the ability of the native toxin to raise levels of cyclic AMP in avian erythrocytes. Using a cytochemical stain for HRP, we found that 9% of control cultured murine neuroblastoma cells bound cholera toxin-horseradish peroxidase conjugates (CT-HRP) on their surfaces after incubations for 1 h at 4 degrees C. Exogenous GM1, the natural receptor of CT, becomes associated in the culture medium with the plasma membranes of these cells so that 96% of cells are stained. Cells preincubated with GM1 at 4 degrees C were exposed to CT-HRP for 1 h at 4 degrees C. After washing, cells were incubated at 37 degrees C for 30 min-24 h. Endocytosis of CT-HRP occurred within 30 min and CT-HRP remained, throughout the 24-h period, in tubules, vesicles, and cisternae often found near the Golgi apparatus; this aggregate of peroxidase-positive elements probably corresponds to Golgi apparatus-endoplasmic reticulum-lysosomes (GERL) of neurons. In metaphase cells, CT-HRP was observed in aggregates of vesicles and tubules clustered near the centriole. Conjugates of HRP with subunit B, the GM1 binding component of CT, were internalized by cells pretreated with GM1 as was CT-HRP. The 9% of neuroblastoma cells binding CT-HRP in the absence of exogenous GM1 internalized the ligand in a manner indistinguishable from that of the treated cells. These findings indicate that, in neuroblastoma cells, a system of vesicles, tubules, and cisternae, analogous to GERL of neurons, is the primary recipient of adsorptive endocytosis of CT bound to endogenous or exogenously introduced GM1.
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PMID:Endocytosis of cholera toxin in GERL-like structures of murine neuroblastoma cells pretreated with GM1 ganglioside. Cholera toxin internalization into Neuroblastoma GERL. 45 74

Conjugates of horseradish peroxidase with the lectins ricin (d-galactose), wheat germ agglutinin (N-acetylglucosamine), phytohemagglutinin (N-acetylgalactosamine), and with cholera toxin (GM1 ganglioside) were used for a cytochemical detection of corresponding termin al carbohydrates, or glycolipids on cell surfaces of cultured neurons and neuroblastoma cells. Cells were labeled at 4 degrees C with the above ligands and their adsorptive endocytosis was studied after incubations at 37 degrees C in a medium free of ligand. Peroxidase was detected by the method of Graham and Karnovsky (J. Histochem. Cytochem. 14:291, 1966). Lectins and cholera toxin underwent endocytosis in cisternae and vesicles of GERL (Golgi-Endoplasmic Reticulum-Lysosome). We suggest that GERL is the primary ercipieint of adsorptively endocytosed plasma membrane "receptor"-ligand complexes which are thus degraded or possibly reutilized (recycling). Wheat germ agglutinin-horseradish peroxidase conjugates used in vivo for studies of retrograde axonal transport were significantly more sensitive than free horseradish peroxidase.
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PMID:The use of lectins and cholera toxin for the detection of surface carbohydrates of cultured neurons and neuroblastoma. 47 60

2The ganglioside compositions of the chick optic tectum and aggregating tectal cell cultures were examined. Both showed similar trends in changes in ganglioside patterns during development. GD3 and GD1b were the predominant gangliosides early in development, while GD1a and several other multisialogangliosides increased in relative amounts with increasing age in vivo and in vitro. Four gangliosides were present early in development which have not previously been reported. These gangliosides are not present at later developmental times suggesting a possible role for them during the critical early stages of nervous tissue differentiation. Some differences were noted when comparing in vivo versus in vitro ganglioside patterns; these differences may possibly be due to the lack of normal retinotectal connections in the cultures. Cytochemical studies on the localization of the presumed cholera toxin--peroxidase binding site GM1 showed conjugate binding correlates with increasing levels of GM1 in the cultures. In older cultures, the conjugate was uniformly localized on all cells and processes in the aggregates. The conjugate also bound to synaptic membranes and intensely stained the synaptic cleft. This latter observation suggests an enrichment of GM1 in the synaptic cleft region.
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PMID:Ganglioside patterns and cholera toxin--peroxidase labeling of aggregating cells from the chick optic tectum. 49 Jan 54

The uptake of macromolecules by nerve terminals which is followed by retrograde axonal transport seems to occur by two different mechanisms, a specific and a nonspecific one. The nonspecific uptake depends on the presence of macromolecules (e.g., horseradish peroxidase) in the vicinity of the nerve terminals at very high concentrations and is enhanced by neuronal activity. In contrast, the specific uptake and subsequent retrograde axonal transport becomes apparent at much lower concentrations of the appropriate macromolecules, depends on the affinity of these ligands for specific binding sites on the surface of the neuronal membrane, and is independent of neuronal activity. The fact that lectins and some bacterial toxins bind to specific membrane glycoproteins or glycolipids allows conclusions to be drawn regarding qualitative and even quantitative aspects of the composition of the plasma membrane of the nerve terminals. 125I-labelled nerve growth factor (NGF), tetanus toxin, cholera toxin, wheat germ agglutinin (WGA), ricin II, phytohemagglutinin (PHA), and concanavalin A (ConA) were injected into the anterior eye chamber of rats where they were taken up by adrenergic nerve terminals and transported retrogradely to the superior cervical ganglion. The saturation of the uptake-transport found for NGF, WGA, choleragenoid and an atoxic binding-fragment of tetanus toxin indicates that limited numbers of binding sites, which showed also different affinities, are present for each ligand on the membrane of the nerve terminals. Competition experiments showed that the binding sites for the ligands investigated are largely independent. Two different classes of binding sites (high affinity--low capacity and intermediate affinity--intermediate capacity) seem to be involved in the saturable retrograde axonal transport of NGF. In contrast, WGA seems to have only a single class of binding-uptake sites with high capacity and relatively low affinity. Strong evidence for positive cooperativity was obtained for the uptake and subsequent transport of the tetanus toxin fragment.
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PMID:Retrograde axonal transport of specific macromolecules as a tool for characterizing nerve terminal membranes. 51 57


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