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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies have indicated that immunoglobulin enhancers are essential for establishing transcriptional competence but not for maintaining the activity of constitutively transcribed genes. To understand the basis for this developmental shift away from dependence on enhancer function, we have investigated the relationship between transcriptional activity and methylation status of the immunoglobulin kappa light-chain genes (kappa genes) in mouse cell lines representing different stages of B-cell maturation. Using pre-B-cell lines in which the level of a critical kappa enhancer-binding factor, NF-kappa B, was controlled by the administration or withdrawal of lipopolysaccharide and plasmacytoma lines that either contain or lack this factor, we studied the properties of endogenous kappa genes and of transfected kappa genes which were stably integrated into the genomes of these cells. In the pre-B cells, the exogenous (originally unmethylated) kappa genes, as well as endogenous kappa genes, were fully methylated and persistently dependent on enhancer function, even after more than 30 generations in a transcriptionally active state. In plasmacytoma cells, the endogenous kappa genes were invariably hypomethylated, whereas exogenous kappa genes were hypomethylated only in cells that contain NF-kappa B and are thus permissive for kappa enhancer function. These results indicate that the linkage of hypomethylation to enhancer-dependent activation of kappa transcription occurs after the pre-B-cell stage of development. The change in methylation status, together with associated changes in chromatin structure, may suffice to eliminate or lessen the importance of the enhancer for the maintenance of the transcriptionally active state.
Mol Cell Biol 1988 Feb
PMID:The coupling between enhancer activity and hypomethylation of kappa immunoglobulin genes is developmentally regulated. 312 93

We describe the purification to apparent homogeneity of the murine immunoglobulin heavy-chain (IgH) enhancer-binding protein mu EBP-E from murine plasmacytoma cells by ion exchange and affinity chromatography. Glycerol gradient sedimentation, UV cross-linking, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis confirm that mu EBP-E is a 45-kilodalton molecular mass protein. Orthophenanthroline-copper chemical nuclease footprinting with purified protein has identified high-affinity binding sites for mu EBP-E within the IgH enhancer at the previously identified site E and at sites within IgH promoters and in the kappa light-chain enhancer. Equilibrium binding studies indicate that the dissociation constants for mu EBP-E binding to site E within the enhancer and to a binding site within the V1 heavy-chain promoter are quite low, about 2 x 10(-11) M. Comparison of four mu EBP-E recognition sequences detects only limited sequence similarity among binding sites.
Mol Cell Biol 1988 Nov
PMID:Purified mu EBP-E binds to immunoglobulin enhancers and promoters. 314 4

The combined effect of heat shock and glucocorticoid hormone (dexamethasone--DM) on plasmacytoma culture cells has been investigated. Fibroblasts and splenocytes were used as control cell types. Heat shock failed to induce the main hsp68 in plasmacytoma cells, however, the rate of synthesis of a constitutive protein (c-hsp70) increased significantly. In general, plasmacytoma cells exhibit hyperthermosensitivity as compared to control. DM treatment before heat shock did not protect plasmacytoma cells against heat damage. Moreover, if DM was present in culture medium for 3 days before heat shock, the synthesis of c-hsp70 was not increased. Heat-shock treatment leads to some decrease in the number of intact glucocorticoid hormone gc-receptors and binding sites in the nucleus. However, the preserved number of intact receptors after heat shock is quite enough for the realization of all glucocorticoid hormone effects. Interestingly, DM itself inhibits the proliferation of plasmacytoma cells. Furthermore, the combined action of heat shock and DM leads to more pronounced inhibition of plasmacytoma cells, depending on the DM doze and the time of heat shock treatment. The role of increased expression of c-myc gene, characteristic for plasmacytoma cells, in all the phenomena observed is discussed.
Mol Biol (Mosk)
PMID:[Combined effect of heat shock and glucocorticoid hormones on cultured mammalian cells]. 318 27

A procedure has been developed for the production of MAb against weakly immunogenic subunits of a multisubunit enzyme. This procedure takes into account the problems of insufficient antigen, single epitope immunodominance and the difficulty of mapping non-sequential determinants. Small quantities of mammalian RNA polymerase II subunits were purified by SDS-polyacrylamide gel electrophoresis and were used to immunize splenocytes in vitro. After fusion with plasmacytoma cells, the hybrid cells were cloned and screened by ELISA utilizing native RNA polymerase II. This procedure is biased towards the production of MAb directed against sequential epitopes accessible on the native enzyme. Monoclonal antibodies, produced by in vitro immunization, were shown to be useful in protein transblot analyses, to inhibit enzyme activity in vitro and to have binding affinities comparable with MAbs produced by in vivo immunization.
Mol Immunol 1988 Oct
PMID:Production of monoclonal antibody against electrophoretically purified RNA polymerase II subunits using in vitro immunization. 321 73

The nuclear extracts of plasmacytomas producing antibodies were found to contain factors which formed complexes with the promoter fragment of the gene for immunoglobulin kappa-chains. The corresponding complexes found in the extracts of nonlymphoid cells had a different mobility. Two approaches were proposed for determining the boundaries of the region necessary for protein factors to be bound to DNA using nuclease Ba131. A 5'-ATTTGCAT-3' octanucleotide sequence was shown to be necessary for interaction with the protein nuclear factor in the studied plasmacytoma lines. The protein completely lost its affinity if at least one nucleotide was removed or substituted at the 5'- or 3'-end of this sequence. The procedures proposed for determining the precise boundaries of the sequence necessary for protein binding to DNA do not require a preliminary protein purification. The principles on which the procedures are based, set no limitations to their application to other systems used for studying the interaction of proteins with DNA.
Mol Gen Mikrobiol Virusol 1988 Oct
PMID:[Factors interacting with promoter region of immunoglobulin genes. Determination of the binding site boundaries]. 323 Dec 28

In mouse cells, the major inducible heat shock protein is a protein of 68,000 daltons (hsp68). We have previously shown that mouse plasmacytomas do not express hsp68. We have now made use of these natural mutants to assess the contribution of hsp68 to acquired thermotolerance. An endpoint limiting dilution assay was used to quantify cell survival to lethal stresses. Two test plasmacytoma cell lines (C1.18.1 and J558) and an hsp68-positive myeloma, XC1.1/51, used as a control, were examined. All showed recovery when pretreated for 10 min at 44 degrees C 2 h before exposure to otherwise lethal stresses of 1 to 4 h at 43 degrees C. Similar results were obtained with the Friend erythroleukemia line D1B, which we have also shown not to express hsp68. These results indicate that hsp68 is not required for protection against thermal stresses in mouse cells.
Mol Cell Biol 1988 Dec
PMID:The major inducible heat shock protein hsp68 is not required for acquisition of thermal resistance in mouse plasmacytoma cell lines. 324 62

The binding thermodynamics of seven different oligosaccharide haptens to the dextran-specific IgM secreted by the murine plasmacytoma MOPC-104E were studied by direct calorimetric measurements. The enthalpy change values observed for the binding process range between -5 and -16 kcal/mol depending on the hapten and the temp of measurement. The antibody-hapten interactions were characterized by a positive heat capacity change [delta Cp approximately 300 cal/(mol.degree)] and a resultant process of enthalpy-entropy compensation. The calculated change in unitary entropy of the reaction, delta Su, ranged between -20 and -30 eu (4 degrees C), corresponding to an expected entropy loss due to immobilization of the hapten molecules. The entropy of binding increased with rising temp, thus compensating for the decreasing enthalpy contribution to the free energy of binding. The data are consistent with a hapten binding induced conformational transition to a more relaxed state in the immunoglobulin molecule.
Mol Immunol 1988 Apr
PMID:Thermodynamics of oligosaccharides binding to a dextran-specific monoclonal IgM. 339 61

The major heat shock gene coding for a 68,000-dalton protein was found to be silent in mouse plasmacytoma MPC-11 in both control and stressed cells. The block appears to be at the level of transcription, although RNA processing or instability has not been ruled out. It is not caused by a major deletion or rearrangement of the gene.
Mol Cell Biol 1985 Jul
PMID:Nonexpression of a major heat shock gene in mouse plasmacytoma MPC-11. 402 12

An "in vivo" study of metaphase degeneration in the murine plasmacytoma (MPC 11) over 8.5 h after mitotic arrest with vincristine sulphate and labelling with 3H-TdR is described. The main points to emerge were that: (1) Metaphase degeneration becomes apparent from the decline in the unlabelled metaphase collection function after 3 to 4 h; (2) the decline is such that by 8.5 h approximately 25% of the metaphases which were present in the tissue at 3 h are no longer identifiable entities; (3) No circadian variation in the mitotic index was found; (4) 3H-TdR may have a retarding effect on the entry of labelled cells into mitosis.
Virchows Arch B Cell Pathol Incl Mol Pathol 1983
PMID:A reappraisal of the stathmokinetic technique. I. An experimental study of a murine plasmacytoma with special reference to metaphase degeneration. 613 92

We have discovered a new class of transcripts of immunoglobulin kappa genes in RNA from B-lineage cells. These transcripts have the properties predicted of free introns excised from kappa mRNA precursors. RNA extracted from populations of normal mouse spleen cells polyclonally activated with B-cell mitogens contains four such transcripts; their electrophoretic mobilities correspond to the distances between the intron-exon boundary of the C kappa region and the four useable J kappa elements, and their relative abundance reflects the relative usage of those J segments. Analysis of RNA from monoclonal kappa-expressing cell lines reveals that one active locus produces one free intron, its size determined by which J element is used in that locus. Apart from their distinctive size, free introns are identified by their lack of polyadenylic acid and their ability to hybridize to cloned probes containing intron sequences, but not to the adjacent V or C exonic sequences. They have a characteristic subcellular distribution, being extractable from nuclei by treatment with nonionic detergent; nuclei thus treated retain most of the primary mRNA precursors, but few of the free introns. A high level of kappa gene expression is not a prerequisite of a cell containing detectable free kappa introns; the lymphoma 38c has only 5% or less of the amount of kappa mRNA that the plasmacytoma MCP-11 contains, yet the ratio of free intron to mRNA precursor is about the same in both cell lines. When analyzed by electrophoretic separation of sufficient resolving power, the free introns due to a single kappa locus resolve into two discrete species. We consider that this most likely reflects the existence of two conformers of the intron, one presumably a covalently intact circle and the other linear molecule.
Mol Cell Biol 1984 Oct
PMID:Introns excised from immunoglobulin pre-mRNAs exist as discrete species. 643 93


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