Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The induction of an antibody response to cholera toxin (CT) was studied by using the synthetic peptide approach. Two peptides, corresponding to the amino acid sequences from residues 57 to 69 (CTBP1) and 47 to 60 (CTBP2) of the cholera toxin B subunit, were synthesized by the solid-phase method. These peptides were primarily chosen on the basis of their hydrophilicity and sequence identity with the B subunit of E. coli toxin (LTh). Synthesized peptides were coupled to carrier proteins through additional cysteine residues at the carboxyl (CTBP1) or amino terminal ends (CTBP2). Rabbit antisera to the peptide-carrier conjugates were found to react with the free peptides as well as intact CT, its B subunit and LTh as determined by the conventional enzyme-linked immunosorbent assay (ELISA). On the other hand, anti-peptide sera failed to react with CT and LTh in GM1 (ganglioside)--ELISA, thereby suggesting the possible involvement of CTBP1 and CTBP2 peptide regions of the toxin molecule in GM1 receptor binding. Both anti-peptide sera possessed rather weak toxin neutralizing activity in the rabbit ileal loop assay. However, such activity was statistically significant (0.02 less than P less than 0.05) only in the case of anti-CTBP2 serum. Similar results were also obtained with mouse polyclonal anti-peptide sera. Ten mouse monoclonal antibodies were obtained against the CTBP1 peptide, five of which reacted to CT, the B subunit and LTh in ELISA. Interestingly, one monoclonal showed strong reactivity against CT and LTh although it reacted very weakly against the immunizing peptide CTBP1. It appears that the immunizing peptide probably exists in multiple conformers in the conjugated form, some of which may mimic more closely its structural features in the intact protein than in the free state. Results obtained in this study suggest that synthetic peptides can serve as useful probes for the structural analysis of CT or related toxins and may be useful in vaccine development.
Mol Immunol 1988 Mar
PMID:Induction of polyclonal and monoclonal antibody responses to cholera toxin by the synthetic peptide approach. 337 93

A monoclonal antibody (MAb) was prepared by the fusion of murine SP2-O myeloma cells with BALB/cByJ spleen cells that were immunized with the glycolipid asialo GM1 adsorbed to naked Salmonella. The specificity of the IgM antibody obtained was defined using various glycolipids, cell extracts and saccharides in ELISA assays and thin-layer chromatography (TLC) immunoblots. The non-reducing terminal galactose is the immunodominant residue for this antibody; however, there is undetectable reactivity to free galactose, galactosylceramide or compounds with an alpha-linked galactose. The SH-34 antibody specifically lyses asialo GM1-expressing macrophages in the presence of complement and removes NK cells in vitro from spleen cell populations. When the specificity of the MAb was compared to that of a commercially available rabbit antiserum to asialo GM1, it was found that both cross-reacted with GM1 and asialo GM3 at high antibody concns; however, the MAb did not bind asialo GM2 while the rabbit antiserum showed substantial reactivity to this glycolipid. It is anticipated that this MAb will be useful for the study of murine and rat natural killer cells.
Mol Immunol 1987 Jan
PMID:A monoclonal antibody with reactivity to asialo GM1 and murine natural killer cells. 361 6

The binding specificity of rat alveolar macrophages (AM phi) for sheep erythrocytes (E) coated with gangliosides GM1, GM2, GM3, GD1a, GD1b or GT1b was analyzed in a rosette assay by studying the inhibitory effect of gangliosides, various carbohydrates, IgG, C3b-like C3, and fibronectin in this assay. The uptake of gangliosides by E was calculated from radioactivity measurements using 3H-labeled gangliosides. The different gangliosides were taken up by E at 37 degrees C to a similar extent. Uptake of 3H-labeled GM2 correlated linearly to its concn in the incubation medium. Erythrocytes pretreated with the same molar concn of GM2, GD1a, GD1b or GT1b were bound to AM phi to the same degree reaching a maximum of about 90% rosette forming cells. A mean of 17.8% AM phi-bound GM3-coated E. Treatment of E with asialo-GM2 (GA2) or GM1 did not induce significant rosette formation. A dose-dependent inhibition of rosette formation was observed when AM phi were preincubated at 0 degree C with GM2, GM3, GD1a, GD1b or GT1b, but not with GM1 or GA2 Of the tested carbohydrates, sialyl-lactose had a strong inhibitory effect, while lactose was completely ineffective. N-acetyl-neuraminic acid, N-glycolyl-neuraminic acid and N-acetyl-galactosamine were slightly inhibitory. A series of other carbohydrates including highly negatively charged compounds, as well as fibronectin, IgG or C3b-like C3 did not show significant inhibition. Our data indicate the expression of a receptor on rat AM phi recognizing carbohydrates containing sialic acid at or near the non-reducing terminus.
Mol Immunol 1986 Nov
PMID:Specificity of ganglioside binding to rat macrophages. 382 40

The murine antibody response to the asialo GM1 adsorbed to stripped Salmonella was studied. IgM and IgG responses were obtained which did not fall to baseline within 200 days after the initial immunization. The antisera from the experimental group showed strong reactivity to asialo GM1 and measureable amounts of activity to asialo GM2. Sera from control animals receiving Salmonella alone also reacted to asialo GM2. Additional experiments showed that the anti-asialo GM1 and the anti-asialo GM2 activities were the result of separate antibody populations. Antisera from an early bleed of the experimental group showed specific lysis of asialo GM1 bearing macrophages; however, later bleeds from both experimental and control groups lysed asialo GM1 expressing and normal macrophages equally. These results suggest an autoimmunity had been generated. The suitability of this protocol for generating specific antiserum and immunizing in preparation for generating monoclonal antibodies is discussed.
Mol Immunol 1985 Nov
PMID:Murine antibody response to the glycolipid asialo GM1 adsorbed to Salmonella. 407 45

The lipid composition of rat spinal cord undergoing postmortem autolysis for 3 min and for 4 h at 38 degrees C was investigated as a model for lipid changes in total spinal cord ischemia. The only change in cords incubated for 3 min was an 11.7% decrease in cholesterol/g fresh weight. The cords incubated for 4 h showed a similar 11.6% decrease in cholesterol/g fresh weight as well as a 5.6% increase in water content and a 22% decrease in phosphatidyl serine. Changes of marginal statistical significance included a 15% increase in lipid phosphorus/g dry wt. and a 15% decrease in G4 (GM1)1 in the 4 h incubated cords. Therefore, autolytic processes are of little consequence in total spinal cord ischemia and attention should now be focused on exogenous pathogenetic factors to explain such ischemic changes in spinal cord. We also report discovery of an alkali-labile ganglioside, G1a in rat spinal cord.
Virchows Arch B Cell Pathol Incl Mol Pathol 1981
PMID:Effects of postmortem autolysis on the lipids of rat spinal cord. 611 47

Gangliosides are neuraminic acid-containing glycolipids preferently localized in nervous membranes and showing physicochemical peculiarities, e.g., drastically changing amphiphilic properties by Ca2+ binding. On account of this they are favorite compounds to act as modulators of membraneous organization and functions during synaptic transmission. Lipid monolayers are suitable experimental systems for the study of the surface behavior of amphipatic molecules and therefore are useful to interpret membraneous organization. The surface pressure/area isotherms of monolayers of different individual gangliosides (GM1, GD1a, GD1b, GT1b) of an artificial reconstituted and a natural ganglioside mixture from bovine brain and of ganglioside mixtures from different brain parts of summer- and winter-adapted dsungarian hamsters were compared at three temperatures (11, 20, and 37 degrees C) with egg phosphatidylcholine (PC) and phosphatidylserine (PS) monolayers. The monolayers were formed in a Teflon trough on a triethanolamine/HCl-buffered (pH 7.4) subphase, in some cases containing different amounts of CaCl2. The surface pressure/area isotherms of ganglioside monolayers, in contrast to phospholipids, generally showed slowly rising slopes, with transitions from the liquid-expanded to the liquid-condensed state at a surface pressure of 20-30 mN/m. Ganglioside monolayers, in particular from GD1a or GT1b versus GD1b or from mixtures from summer- versus winter-adapted hamster brain, were differently affected by temperature and/or by Ca2+. PS monolayers were slightly condensed only by Ca2+. PC monolayers, however, were influenced neither by temperature nor by Ca2+. In mixed monolayers of the unpolar natural lipid cholesterol (Ch) and the disialoganglioside GD1a, intermolecular interactions were indicated. Ganglioside monolayers, in contrast to phospholipids, were shown to be easily modulated by temperature and/or Ca2+ ions, thus enabling gangliosides to act as possible membrane modulators, e.g., during synaptic transmission. In particular, the differences concerning the influences of temperature and/or Ca2+ on the surface behavior of ganglioside mixtures from the brain of summer- compared with winter-adapted hamsters are correlated with other physiologically relevant data.
Cell Mol Neurobiol 1984 Jun
PMID:Modulatory effects of different temperatures and Ca2+ concentrations on gangliosides and phospholipids in monolayers at air/water interfaces and their possible functional role. 648 44

The B, or binding, subunit of cholera enterotoxin forms a pentameric ring structure in the intact toxin, and also when the subunit is isolated from the A subunit. The thermal denaturation of the B subunit ring was examined by differential scanning calorimetry in the presence and absence of ganglioside GM1, its natural 'receptor'. In the absence of ganglioside an irreversible endotherm was observed with maximal excess apparent heat capacity, Cmax, at 74.6 degrees C. When the ganglioside was added in increasing amounts, multiple transitions were observed at higher temperatures, the most prominent having a Cmax at 90.8 degrees C. At high ganglioside concentrations, the 74.6 degrees C transition was not observed. In addition to the thermodynamic results a model is proposed for the interaction of GM1 and B subunit pentamer. This model is derived independently of the calorimetric results (but is consistent with such data) and is based upon considerations of the geometry of the GM1 micelle B subunit pentamer.
Mol Cell Biochem 1984 Aug
PMID:Effects of ganglioside GM1 on the thermotropic behavior of cholera toxin B subunit. 649 15

The addition of 88 mM sucrose to the culture medium of human skin fibroblasts from normal subjects caused remarkable increase in the intracellular lysosomal hydrolase activities. The mechanism of this induction by sucrose loading was carefully studied with several fibroblast strains of different inherited lysosomal storage disorders. In single lysosomal hydrolase defect such as GM1-gangliosidosis, mannosidosis and Sandhoff disease, no induction of the deficient hydrolase was found with 88 mM sucrose loading. In contrast, sucrose loading caused normalization of intracellular lysosomal hydrolase activities in I-cell disease fibroblasts and cytoplasmic inclusion materials disappeared. Subsequent investigations reveal that I-cell disease cells are classified into three subgroups by the degree of hydrolase induction by sucrose loading; a high responding, an intermediate responding and a no-response group. The heterogeneity may be based upon different induction by sucrose loading of the enzyme, probably the residual phosphotransferase which is involved in the processing steps of lysosomal enzyme molecules. With the addition of mannose-6-phosphate and 10 mM NH4Cl to cultured skin fibroblasts, it was shown that sucrose loading caused increased synthesis of lysosomal enzyme proteins. The result of the test with 2,4-dinitrophenol suggests that sucrose is indeed pinocytosed by cultured human skin fibroblasts and localized in lysosomes and that this event is the essential factor to trigger the induction of lysosomal hydrolases. Simultaneous loading of both invertase and sucrose in cultured cells caused no induction of alpha-mannosidase activity. This result indicates that invertase is also pinocytosed, reaches the lysosomes and hydrolyzes sucrose in the lysosomes. Lysosomal overloading with sucrose resulted in induction of lysosomal hydrolases and invertase blocked the induction of alpha-mannosidase activity. However, some induction still exists in beta-galactosidase and alpha-fucosidase activity. Thus it is very likely that the induction of lysosomal hydrolases demands a complicated process. In this article, we investigated the effects of sucrose on the lysosomal hydrolases in cultured human skin fibroblasts of several inherited lysosomal storage disorders and normal subjects and discuss the possible mechanism of the induction of lysosomal hydrolase activities by sucrose loading.
Mol Cell Biochem 1984
PMID:The effects of sucrose loading on lysosomal hydrolases. 670 43

Cholera toxin (CT) covalently linked to horseradish peroxidase (HRP) is a specific cytochemical marker for its receptor, the monosialoganglioside GM1. The binding and endocytosis of exogenous [3H]GM1 by cultured murine neuroblastoma cells (line 2A [CCl-131] ), which contain predominantly GM3, was examined by quantitative electron microscope autoradiography. The relationship between exogenous receptor, [3H]GM1, and CT HRP was studied in double labeling experiments consisting of autoradiographic demonstration of [3H]GM1 and cytochemical visualization of HRP. Exogenous [3H]GM1 was not degraded after its endocytosis by cells for 2 h at 37 degrees C. Quantitative studies showed similar grain density distributions in cells treated with [3H]GM1 alone and in cells treated with [3H]GM1 followed by CT-HRP. Qualitative studies conducted in double labeling experiments showed autoradiographic grains over the peroxidase-stained plasma membrane, lysosomes, and vesicles at the trans aspect of the Golgi apparatus. The findings indicate that exogenous glycolipid is associated with the plasmid membrane of deficient cells and undergoes endocytosis. The quantitative ultra-structural autoradiographic studies are consistent with the hypothesis that the spontaneous endocytosis of exogenous [3H]GM1 controls the subsequent uptake of CT-HRP.
Mol Cell Biol 1983 Jan
PMID:Endocytosis of exogenous GM1 ganglioside and cholera toxin by neuroblastoma cells. 682 31

On t.l.c. plates 125I-cholera toxin binds to a disialoganglioside tentatively identified as GD1b with about 10 times less capacity then to ganglioside GM1. Binding of labeled toxin to both gangliosides was abolished in presence of excess amounts of unlabeled B subunit. Ganglioside extracts from human or pig intestinal mucosa showed toxin binding to gangliosides GM1 and GD1b. In ganglioside-containing lipid monolayers the penetration of the toxin was independent of the ganglioside binding capacity.
Mol Cell Biochem 1982 Aug 06
PMID:Ganglioside-cholera toxin interactions: a binding and lipid monolayer study. 712 55


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