Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026764 (multiple myeloma)
 36,148 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The receptor for transferrin is one of the major surface proteins of proliferating lymphocytes and other cells. It binds ferrotransferrin from serum and endocytoses it into an acidic nonlysosomal intracellular compartment where iron is released, but in which apotransferrin remains tightly bound to its receptor. Recycling of the apotransferrin-receptor complex to the cell surface is associated with a return to neutral pH and concomitant loss of affinity of apotransferrin for its receptor. Apotransferrin is then free to leave the cell and initiate a new cycle. We have exploited this cycle in a novel method for the purification of the receptor for transferrin. Murine myeloma cells were lysed in nonionic detergent, and the lysate passed over a column of ferrotransferrin-agarose at pH 7.4. After washing with sodium acetate at pH 5.0, iron was removed with sodium citrate pH 5.0 and desferrioxamine. Upon returning the pH to neutrality, the receptor was eluted and found to be homogeneous by SDS-polyacrylamide gel electrophoresis under both reducing and nonreducing conditions. The degree of purification was estimated to be at least 3,000-fold, and the calculated yield was 10 to 20%. The purified receptor was capable of binding to transferrin. The receptor was digested with trypsin, and the resulting peptides were separated by reversed-phase high performance liquid chromatography in NH4HCO3. Selected peptides were rechromatographed in 0.1% trifluoroacetic acid, and their amino acid sequences were determined.
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PMID:The receptor for transferrin on murine myeloma cells: one-step purification based on its physiology, and partial amino acid sequence. 609 68

Monoclonal antibodies were used to study p97, a human melanoma-associated antigen (MAA). Four hybridomas, designated 4.1, 96.5, 118.1, and 8.2, were obtained by fusing mouse myeloma cells with spleen cells from mice immunized with human melanoma cells. Antibodies 4.1 and 8.2 were IgG1; antibodies 96.5 and 118.1 were IgG2a. Sequential immunoprecipitation (IP) and sodium-dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that all 4 antibodies recognized the same 97 kilodalton (kD) protein. Binding studies with 125I-labeled antibody showed that antibodies 4.1 and 96.5 bound the same epitope, p97a. Antibodies 118.1 and 8.2 defined epitopes p97b and p97c, respectively. Six monoclonal antibodies (M17, L1, L10, R10, I12, and K5) specific for gp95, a kD melanoma cell surface glycoprotein were also tested. Sequential IP showed that these antibodies bound p97; p97 and gp95 are thus identical. Binding studies showed that antibody m17 bound epitope p971, and antibodies L1, L10, and R19 bound epitope p97c. Antibodies I12 and K5 defined 2 other epitopes, p97d and p97e, respectively. SDS-PAGE under nonreducing conditions indicated that p97 is monomeric, probably with intrachain disulfide bonds. Cell-surface labeling of sialic acid residues and neuraminidase digestion showed that p97 is a sialoglycoprotein. Digestion of p97 with papain or trypsin produced a stable 40 kD fragment, which expressed epitopes p971, p97b, and p97c, but not p97d or p97e.
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PMID:Structural characterization of human melanoma-associated antigen p97 with monoclonal antibodies. 616 74

To characterize the Fc receptors on rat alveolar and peritoneal macrophages (M phi), we analyzed their ability to form rosettes with fixed ox erythrocytes (Eo') coated with myeloma proteins of all rat Ig classes and with fresh erythrocytes (Eo) sensitized with rat IgG1 and IgG2, rabbit IgG and IgM, and mouse IgA antibodies. The M phi formed rosettes with Eo' coated with rat myeloma proteins of classes IgG1, IgG2a, IgG2b, and IgE but not IgG2c, IgA, IgM, and IgD. Rat M phi also formed rosettes with Eo' coated with human IgG1, IgG3, IgG4, mouse IgG1, IgG2a, IgG2b, and rabbit IgG. Furthermore, rat M phi formed rosettes with Eo sensitized with rat IgG1, IgG2, or rabbit IgG antibodies but not with Eo sensitized with rabbit IgM or mouse IgA antibodies. Trypsin treatment of rat M phi abolished IgG1/IgG2b and IgE but not IgG2a rosettes. The IgG2a and IgE rosettes were Ig class specific because they were inhibited only by rat IgG2a and rat IgE, respectively. In contrast, IgG1 and IgG2b rosettes were inhibited equally by IgG1 and IgG2b. Heterologous IgG inhibited IgG1/IgG2b but not IgG2a rosettes. Rat IgE inhibited rat IgG1, IgG2b, and heterologous IgG rosette formation on rat M phi. Although Eo' coated with rat IgE formed rosettes with mouse P388D1 macrophagelike cells, rat IgE did not inhibit IgG rosettes on these cells. Similarly, Eo' coated with human IgE formed rosettes with human U937 macrophage-like cells, but human IgE did not inhibit IgG rosettes on these cells. The results indicate that rat M phi have at least three distinct Fc receptors: one is specific for rat IgG2a and is trypsin resistant; a second is specific for rat IgE and is trypsin sensitive; and a third reacts with rat IgG1 rat IgG2b, and heterologous IgG and is trypsin sensitive. Rat IgE inhibited IgG1/IgG2b rosettes undirectionally and uniquely on rat M phi.
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PMID:Specificity of fc receptors for IgG2a, IgG1/IgG2b, and IgE on rat macrophages. 616 53

Two monoclonal IgG3 (kappa) antibodies against murine Thy-1.2 antigen produced by murine 1B5 and 1aG4/C5 hybridomas were partially characterized. The 1aG4/C5 antibody has slightly higher affinity for the Thy-1.2 antigen in binding tests and more efficiently kills the Thy-1.2+ thymocytes in cytotoxicity assays as compared to the 1B5 antibody. The latter, in addition, reacts significantly with the Thy-1.1 antigen (the allelic form of Thy-1 antigen expressed on the cells of the donor of the immune cells. Both monoclonal antibodies exhibit some characteristic properties of IgG3 of myeloma origin, e.g. a tendency to aggregation, high pI and interaction with protein A. Our monoclonal antibodies are sensitive to pepsin digestion, resistant to trypsin, their disulphide bonds are rapidly cleaved by sulphitolysis and reduction by dithiothreitol. They possess characteristic acidic peptides bearing the disulphide bonds between the heavy chains. These antibodies, however, differ to some extent from each other in some properties (precipitation with staphylococcal protein A, solubility, pI, electrophoretic behaviour of the light chains). They possess different heavy chain peptides bearing the interchain disulphide bonds and thus they probably differ in the hinge region. This structural difference may be associated with different sensitivity of these two antibodies to sulphitolysis and proteolysis.
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PMID:Monoclonal IgG3 (kappa) antibodies against murine Thy-1.2 antigen produced by murine hybridomas. Differences in the specificity of the antigen binding site and in the structure of the hinge region. 618 35

Four mouse monoclonal antibodies directed against the red cell membrane protein glycophorin A have been isolated and characterized. They are produced by hybridomas derived from SP2/0 myeloma cells and spleen cells from Biozzi mice immunized with a mixture of human erythrocytes from homozygous blood group M and N individuals. These antibodies recognize and bind to purified glycophorin A and to glycophorin on the red cell surface. All are of the IgGl, kappa light chain subclass and bind to determinants presented on the 39 amino acid, trypsin-sensitive, N-terminal peptide of glycophorin A. Three display differential specificities for the two allelic forms of glycophorin A; two are exquisitely specific for the M-form and one preferentially binds the N-form. Treatment of red cells with neuraminidase, which removes N-acetylneuraminic acid from glycophorin A, abolishes the binding of these three antibodies. The binding of the N-specific antibody is also sensitive to modification of the amino-terminal residue of the antigen. The fourth antibody binds equally well to both the M- and N-forms as well as to neuraminidase-treated red cells; thus it recognizes a public, N-acetylneuraminic acid independent glycophorin A determinant.
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PMID:Monoclonal antibodies specific for the M- and N-forms of human glycophorin A. 619 36

Fusion of splenic lymphocytes from Lewis rats, immunized with affinity-purified estrogen receptor from the cytosol of MCF-7 human breast cancer cells, with two different mouse myeloma lines, has provided 13 monoclonal hybridoma lines secreting antiestrophilin antibodies, each of which (with one possible exception) recognizes a different antigenic determinant in the human receptor molecule. Of this library of monoclonal antibodies, some react with estrophilin from all sources tested, some react with mammalian but not avian receptors, whereas one preparation appears specific for estrophilin from primate sources. By proteolytic digestion under controlled conditions with mercury-deactivated papain, chymotrypsin, and trypsin, respectively, it is possible to remove sequentially the determinants recognized by one, two or three of the monoclonal antibodies, leaving the epitopes for the six remaining antibodies investigated on the steroid-binding portion of the receptor. The proteolytic fragment containing the epitope most readily removed (by mercuripapain) also contains the DNA-binding domain of the activated receptor molecule. Immunocytochemical staining, using the peroxidase procedure with various monoclonal antibody preparations, of frozen sections of human breast cancer tissue, fixed in ethanol or in picric acid-formaldehyde reagent, shows clearly that the majority of the native receptor, which appears in the cytosol after tissue homogenization, is actually localized within the nuclear compartment in the intact cell. The immunocytochemical technique also permits the identification of mixed populations of receptor-containing and non-containing cells in human breast cancers.
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PMID:Immunochemical studies of estrogen receptors. 620 Jul

The regulation of human IgE production in vitro by soluble T cell factors was examined. T cells were isolated from the peripheral blood of 2 patients with the hyper-IgE syndrome on the basis of their expression of Fc receptors for human IgE (Fc epsilon R). The T cells were incubated with human myeloma IgE (10 micrograms/ml), washed, reacted with immunosorbent-purified goat anti-human IgE conjugated with fluorescein isothiocyanate, and then separated into Fc epsilon R+ and Fc epsilon R- T cells on the fluorescence-activated cell sorter. Fc epsilon R+ T cells and Fc epsilon R- T cells were propagated in culture using supernatants of phytohemagglutinin-stimulated peripheral blood mononuclear cells (PBMC) and irradiated autologous PBMC. Supernatants of Fc epsilon R+ T cell lines but not of Fc epsilon R- T cell lines selectively enhanced IgE synthesis in cultures of B cells obtained from patients with allergic rhinitis but not from normal nonallergic subjects. The surface phenotype of the Fc epsilon R+ T cell line was predominantly T3+, T4+, Ia+ with few (15%) T8+ cells. Two T cell clones were grown from the Fc epsilon R+ T cell line by limiting dilution (0.3 cells/well). These clones possessed the T4+ helper/inducer phenotype and secreted IgE-enhancing factor(s). The IgE-enhancing factor(s) which had affinity for insolubilized human IgE was sensitive to treatment with trypsin and neuraminidase, and had as its target an IgE-bearing B cell. These results suggest that a subset of human T cells bearing an Fc epsilon R secretes an IgE-binding glycoprotein which selectively enhances IgE synthesis by IgE-bearing B cells.
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PMID:Production of IgE-potentiating factor in man by T cell lines bearing Fc receptors for IgE. 623 18

A mouse helix-destabilizing protein (HD protein-1) has been purified and characterized, and controlled tryptic digestion has been used to generate two large fragments of this protein and to study structural changes accompanying DNA binding. HD protein-1, a DNA-binding protein that has higher affinity for single-stranded DNA (ssDNA)-cellulose than for double-stranded DNA (dsDNA)-cellulose and is resistant to a dextran sulfate elution from ssDNA-cellulose, was purified from mouse myeloma by the method described by Herrick and Alberts (Herrick, G., and Alberts, B. M. (1976) J. Biol. Chem. 251, 2124-2132). HD protein-1 was heterogeneous with regard to apparent molecular weight (range of Mr = 24,000 to 33,000), but individual Mr species shared extensive primary structure homology as revealed by tryptic peptide mapping. The predominant species of this protein, Mr = 27,000, was resolved from other species and obtained in nearly homogeneous form by preparative isoelectric focusing. Mouse HD protein-1 was capable of lowering the Tm of poly[d(A-T)] by 25 degrees C, indicating that it is a helix-destabilizing protein. Sedimentation boundary analysis revealed that binding to ssDNA was noncooperative and that the binding site covered about 6 nucleotide residues. There was a 35% increase in the intrinsic tryptophan fluorescence of the protein in the presence of ssDNA, suggesting that structural change accompanies binding. Subcellular localization studies indicated that 75% of mouse HD protein-1 is nuclear, but not chromatin-associated, and primary structure analysis indicated that HD protein-1 is distinct from high mobility group proteins 1 and 2, histones, and P8 protein. Tryptic hydrolysis of HD protein-1 produced discrete, large fragments whose apparent molecular weights ranged from 19,000 to 24,000, and whose relative abundance was changed by the presence of ssDNA during the digestion. Thus, a Mr = 22,000 fragment (22 HDP*) predominated in the absence of ssDNA, and a Mr = 19,000, fragment (19 HDP*) predominated in the presence of ssDNA. Poly(dT) and denatured calf thymus DNA were more effective than were other polynucleotides tested in promoting accumulation of 19 HDP*; (dT)8 was as effective as were longer molecules of (dT)n, but (dT)4 and (dT)6 were much less effective, indicating that the binding site involved in 19 HDP* accumulation covered between 6 and 8 residues of (dT)n. Both 19 HDP* and 22 HDP* have the same COOH-terminal end and the same affinity for ssDNA-cellulose as does the native HD protein-1, indicating that a Mr = 8,000 sequence at the NH2-terminal end of HD protein-1 is not required for binding to ssDNA. Even though 22 HDP* retained the ability to bind to ssDNA, it could not be converted to 19 HDP* by further trypsin digestion.
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PMID:Studies on the structure of mouse helix-destabilizing protein-1. DNA binding and controlled proteolysis with trypsin. 625 73

The immunosuppressive effect of splenic macrophages (M phi) in mice bearing plasmacytoma was previously shown to be mediated by a diffusible factor. This diffusible suppressor factor (DSF) was found to be non-dialysable and sensitive to heating to 56 degrees C and to the proteolytic action of trypsin. The suppressor factor could be removed from culture supernatants by binding to ligands that specifically bind to corresponding myeloma proteins. DSF from splenic suppressor M phi of mice bearing MOPC 315 was capable of binding dinitrophenyl L-lysine, and that from mice bearing MOPC 104E, dextran S. The suppressor factor apparently cross-reacted with anti-idiotypic antibody to the corresponding myeloma protein, but did not interact with anti-isotypic antibody to mouse immunoglobulins (Ig). A higher concentration of mouse Ig than that found in DSF preparations did not have a suppressive effect. Metabolic inhibitors for RNA and protein, but not DNA synthesis effectively blocked the production of DSF. These findings suggest that DSF is a non-Ig protein that may have a structural similarity to myeloma idiotype. Continuous RNA and protein synthesis is required for the elaboration of DSF by splenic suppressor M phi in cultures.
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PMID:Diffusible suppressor factor from splenic macrophages in murine plasmacytoma. 637 61

A monoclonal antibody (iB5, IgG1 kappa) reacting with human red cells was produced after immunization of BALB/C mice with cord red cells, followed by fusion of the spleen cells with the murine myeloma cell line Ag 8-653. The monoclonal antibody agglutinated blood group N+ much better than M + N-red cells but did not recognize erythrocytes from rare individuals typed as M + N-S-s-U- and those from an En(a-) individual (M.E.P.). However, S-s-U- donors typed as M + N + or M-N+ and En(a-) red cells from donor G.W. were agglutinated. The erythrocyte receptors for iB5 are completely destroyed by papain treatment and significantly decreased by neuraminidase. Interestingly also, the iB5 antibody failed to agglutinate trypsin-treated N+M-S-s-U- erythrocytes. Other investigations have shown that the monoclonal antibody precipitated glycophorin A and B from N+ red cells and only glycophorin B from M+N-erythrocytes. The reactivity of iB5 was further explored by immunostaining following the electrophoretic transfer to nitrocellulose sheets of membrane proteins from common (M and N) and rare erythrocytes [En(a-),S-s-U-, MgMg, McM, St(a+), Mi.V, Mi.III, Tn] separated by SDS-polyacrylamide gel electrophoresis. These studies have clearly demonstrated that the monoclonal iB5 antibody is directed against the homologous N-terminal domain of glycophorin A and B, a specificity which explains the serological reactivity of iB5 against common and rare erythrocytes.
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PMID:A monoclonal antibody directed against the homologous N-terminal domain of glycophorin A and B. 640 Oct 2


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