Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have characterized a set of 15 monoclonal antibodies to p19gag, one of the internal proteins of avian sarcoma and leukaemia viruses. All the antibodies work in immune precipitations as well as in immunoblotting, though with different efficiencies. We have developed a simple epitope mapping technique, which uses partial chemical cleavages at methionine or tryptophan residues followed by immunoblotting from SDS-polyacrylamide gels, to localize the epitopes of nine of these antibodies. The epitopes fall into at least four classes. The mapping procedure should also be useful for other antigens of known primary structure.
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PMID:Epitope mapping of monoclonal antibodies to gag protein p19 of avian sarcoma and leukaemia viruses. 244 26

Monoclonal antibodies 50B4 and 50E6 recognize two distinct epitopes of human p85 glycoprotein (CDw44). Both epitopes are destroyed by reduction of the purified glycoprotein as demonstrated by inhibition of cellular radioimmunoassay and Western blot analysis. Endoglycosidase F treated p85 glycoprotein, with an apparent molecular weight of 73,000, is still reactive with both monoclonal antibodies. Thus both epitopes are conformational determinants of the polypeptide chain. A rabbit antibody produced against purified native p85 glycoprotein also reacted only with the non-reduced form of p85. Repeated immunizations with SDS-dissociated and reduced p85 yielded a polyclonal antibody reactive by Western blot analysis with reduced and non-reduced forms of p85 glycoprotein. When a HOON leukemia cell line cDNA expression library was screened with this polyclonal antibody, two cDNA clones were isolated which reacted specifically with the antiserum and not with the control non-immune serum. Preliminary characterization of these clones indicates that they are p85-related.
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PMID:Several epitopes of p85 glycoprotein (CDw44) are dependent on intact disulphide bonds. Isolation of cDNA clones requires a polyclonal antibody raised against the reduced protein. 246 Dec 31

Derivatives of the antiallergic drug cromolyn [disodium 5,5'-[(2-hydroxy-1,3-propanediyl)-bis(oxy)]bis [4-oxo-(4H-1-benzopyran)-2- carboxylate]], which can be conjugated covalently at the propane 2-position to macromolecules and to insoluble matrices, were synthesized. Conjugates of these derivatives with macromolecules were examined for their binding to cells of the rat basophilic leukemia line RBL-2H3, which is widely employed as a model for immunologically induced mast cell degranulation. Only those drug-protein conjugates in which the cromolyn analogue with an amino group at the propane 2-carbon instead of the hydroxyl was linked to the carrier by glutaraldehyde were found to exhibit specific and saturable binding to these cells. Analysis of the binding data for these conjugates yielded an apparent binding constant of 3.8 +/- 0.2 X 10(8) M-1 and an apparent number of binding sites for the probe of 4000-8000 per cell. The conjugates found to bind specifically to the cells were also immobilized on agarose matrices and employed in an affinity-based isolation of the membrane component responsible for the observed binding. A single labeled polypeptide was eluted from these columns, onto which either whole cell lysates or solubilized purified plasma membranes of surface-radioiodinated RBL-2H3 cells had been adsorbed. This membrane protein appears on autoradiograms of nonreducing SDS-PAGE as a single broad band of approximately 110,000 daltons (Da) apparent molecular mass. On autoradiograms of reducing gels, the only band detected has an apparent mass of approximately 50,000 Da and appears narrower. Elution of the columns with the drug and disulfide-reducing agents or with the latter alone resulted in significantly higher yields of the 50-kDa polypeptide. Both the intact and reduced proteins bind strongly to immobilized concanavalin A and less so to immobilized wheat germ agglutinin, suggesting that the isolated intact protein is probably a dimer of two glycosylated subunits of similar molecular mass. Treatment of the reduced protein with endoglycosidase F leads to a decrease in its apparent molecular mass by approximately 12 kDa, suggesting that the extent of glycosylation of this polypeptide is approximately 25%. As shown in the following paper, the intact protein constitutes a Ca2+ channel that is activated upon IgE-Fc epsilon receptor aggregation.
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PMID:Isolation and purification of an Fc epsilon receptor activated ion channel from the rat mast cell line RBL-2H3. 246 4

We have determined the organization and nucleotide sequence of the gene encoding the human T cell surface glycoprotein CD8 alpha. This gene spans approximately 8 kb and is organized into six exons which encode separate functional domains of the protein. Exon 1 encodes the 5' untranslated region and leader peptide, exon II the Ig V-like region, exon III the hinge-like region, exon IV the transmembrane domain, and exons V and VI the cytoplasmic tail. Alternative splicing that excludes nucleotide sequences from exon IV results in a transcript which encodes a secreted form of the protein. This transcript accounts for approximately 15% of the total CD8 alpha mRNA in human T cell leukemia lines and in normal human tissues. Secreted CD8 alpha protein can be detected in culture supernatants of T cell leukemia lines and PHA-stimulated PBMC by immunoprecipitation with the anti-CD8 alpha mAb OKT8 or with a polyclonal rabbit antiserum specific for the 28 amino acid cytoplasmic domain of CD8 alpha. The secreted CD8 alpha protein forms homodimers; when analyzed by SDS-PAGE, the protein migrates with an apparent molecular mass of 27 or 54 kDa under reducing or non-reducing conditions, respectively. Human secreted CD8 alpha may serve an immunoregulatory role for the interactions of T cells with their targets in vivo.
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PMID:Alternatively spliced mRNA encodes a secreted form of human CD8 alpha. Characterization of the human CD8 alpha gene. 249 67

We have found that preparations of rate-zonal purified Moloney murine leukemia virus originally obtained from the National Cancer Institute Resources Program, when separated by SDS-PAGE in the absence of mercaptoethanol (beta-MSH), exhibited a doublet envelope glycoprotein band of approximately 69/67 kD. When the same samples were run in the presence of beta-MSH, a single band at 70 kD (gp70) was observed. Western blot analysis with polyclonal antiserum identified both the 69- and 67-kD bands as envelope gene products. Tryptic peptide mapping of each of the gp67 and gp69 bands confirmed the serological data, with each showing conserved as well as unique peptides. These results imply that the Moloney murine leukemia virus samples examined above contain two structurally different envelope gene products. Western blot analysis using ecotropic and dualtropic specific sera suggest that gp69 is derived from an ecotropic virus, while gp67 is from a dualtropic virus. This is consistent with the results of an earlier study which showed that the majority of the cysteines (4/5) in dualtropic gp70 are lost by a single deletion relative to the ecotropic gp70 species. This would account for the difference in mobility observed in the SDS-PAGE profile in the absence of beta-MSH. It would indicate that the cysteines play an important role in defining structural differences that separate the ecotropic and dualtropic gp70s.
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PMID:Reduction-modifiable properties of Moloney murine leukemia virus gp70 as an indicator of envelope glycoprotein heterogeneity. 252 96

The glycoprotein gp51 of bovine leukaemia virus (BLV) has been included in an immunostimulating complex (ISCOM). The ISCOM was characterized biochemically in SDS-polyacrylamide gel electrophoresis showing the presence of proteins of estimated molecular weights of 50 and 30 kDa. Immunoblotting showed that gp51 was present in the ISCOM. The BLV-ISCOM had a S-value of 19 S and the electronmicrograph showed the cage-like structure as previously reported for other ISCOMs. About 17% of the total amount of gp51 in the cell culture fluid was recovered in the ISCOMs. The largest loss of gp51 was encountered during the sedimentation of the virus. An ELISA, utilizing monoclonal antibodies to defined epitopes for capture was developed to control the antigenicity of epitopes, e.g. those known to induce neutralizing antibodies. Using this device as a quality control for epitopes the following could be stated. First, ISCOMs prepared from virus solubilized with the non-ionic detergents Triton X-100 or MEGA did not react with neutralizing monoclonal antibodies. In contrast, ISCOMs prepared from virus solubilized with the non-ionic detergents Tween-20, Tween-80 or octyl glucoside did react with the neutralizing antibodies. Second, the neutralizing epitopes were better exposed in ISCOMs than the other epitopes of gp51. In a preliminary experiment it was shown that gp51 in ISCOMs was highly immunogenic.
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PMID:Bovine leukaemia virus ISCOMs: biochemical characterization. 254 75

By means of SDS PAGE we isolated from virus-infected foetal lamb kidney (FLK) cells a relatively homogenous envelope transmembrane protein gp30 of bovine leukaemia virus (BLV). As shown by a partial sequence analysis of the N-terminus of this protein, our gp30 preparation contained only traces (less than 5%) of p24 gag protein: Rabbit anti-gp30 serum did not cross react with the BLV proteins gp51, p12, p15(1), p15(2), and p10 but reacted weakly with the p24 polypeptide. 125I-labelled gp30 (chloramine-T) was precipitated with the serum of BLV-infected cattle. Nonlabelled preparation of gp30 competitively inhibited the reaction of 125I-labelled gp30 with the natural antibodies. We investigated 193 cattle sera by liquid phase radioimmunoassays (RIA) using 125I-gp30, gp51 and p24 antigens. Sixteen noninfected cattle sera were negative in all tests. The 177 serum samples of BLV-infected animals were examined to the diagnostic value of the three tests. Of these, 175 were positive in gp51 RIA, 172 in p24 RIA and 164 in gp30 RIA. In all three tests, 159 sera were positive while 18 sera, mostly coming from animals with normal leukocyte counts, were positive only either with gp51 or p24, or were double positive with either gp51/p24 or gp51/gp30. We conclude that the gp51 RIA is superior to both the gp30 and the p24 RIA and that the gp30 RIA will be useful for investigating the role of gp30 in virus pathogenicity.
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PMID:A radioimmunoassay detecting the bovine leukaemia virus transmembrane protein gp30 and anti-gp30 antibodies in the serum of cattle. 256 6

Apoprotein part of tissue factor of human placenta was purified 871 fold from the starting material with 4.2% yield by concanavalin A-Sepharose affinity chromatography and SDS-PAGE. The molecular weight of purified apoprotein was 45,000 in non-reduced condition and 49,000 in reduced condition. Tissue factor of human leukemia cells (FAB classification:M2 and M3) and cultured leukemia cell lines (HL-60 and Molt-4) was analyzed using specific rabbit anti-tissue factor IgG raised against purified material. Endotoxin stimulated HL-60 and Molt-4 also expressed procoagulant activity which was inhibited by tissue factor immune IgG. By immunostaining of the purified material, the lysate of leukemia cells (M2 and M3) and cultured leukemia cells (HL-60 and MOLT-4) revealed a major band of the same apparent molecular weight. Immuno-electron microscopic study on tissue factor of HL-60 cells produced the following findings: stimulation by endotoxin resulted in the formation of pseudopods of the cell membrane, and immunogold particles accumulated mainly on these pseudopods and cisternal spaces of rough endoplasmic reticulum, indicating exposure of the tissue factor to the surface of perturbed cell membrane with concurrent increase in tissue factor synthesis.
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PMID:Studies on leukemic cell tissue factor. 266 Mar 21

Immunostimulating complexes (ISCOMs) have been prepared from feline leukaemia virus (FeLV) envelope proteins. The ISCOMs were characterized biochemically in SDS-polyacrylamide gel electrophoresis showing the presence of proteins of estimated molecular weights of 15,000, 27,000 and 70,000. Immunoblotting showed that both the transmembrane protein p15E and the external glycoprotein gp70 (making up the gp85 protein) were present in the ISCOM. Furthermore, a degradation product of gp70 with an estimated molecular weight of 32,000 was identified in the immunoblot. The FeLV ISCOM was shown by electron microscopy to have the characteristic cage-like structure of an ISCOM with a mean diameter of 37 nm. About 10% of the total amount of gp70 in the culture fluid was recovered in the ISCOMs. The largest loss was encountered during the sedimentation of the virus. In a preliminary immunization experiment in mice the FeLV ISCOMs elicited after a booster gave a clear-cut immune response against gp70.
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PMID:Formation and characterization of FeLV ISCOMs. 275 Feb 72

Protein kinase C (PKC) was purified to near homogeneity from human leukemia ML-1 cells. The purified enzyme showed a single polypeptide band of 80 kDa on SDS-polyacrylamide gel after electrophoresis, and was totally dependent on Ca2+/phospholipid for activity. Diacylglycerol and the tumor-promoting on Ca2/phospholipid for activity. Diacylglycerol and the tumor-promoting phorbol esters stimulated the enzyme activity. Autophosphorylation of PKC purified from phenyl-Sepharose column showed both 80- and 37 kDa polypeptides. Further fractionation of PKC on a hydroxyapatite column revealed two peaks of enzyme activity, indicating that there may be two different forms of protein kinase C present in human leukemia cells. The purified PKC was used to phosphorylate RNA polymerase II of human leukemia cells in vitro and the autoradiogram showed that RNA polymerase II large subunits (240, 220 and 150 kDa) were phosphorylated in a time-dependent manner.
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PMID:Isolation and purification of protein kinase C from human leukemia ML-1 cells phosphorylation of human leukemia RNA polymerase II in vitro. 275 42


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