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

1. A radioactive binding assay for Thy-1.1 alloantigen which functions in the presence of detergents was established by using glutaraldehyde-fixed thymocytes as target cells. Thy-1.1 activity in detergent extracts was then assayed by measuring inhibition of the binding assay. 2. Solubilization of Thy-1.1 from whole thymocytes, and their membranes by a large number of non-ionic detergents and deoxycholate was studied. In the same extracts Ag-B(4) histocompatibility antigenic activities were measured. With the exception of Nonidet P-40, the detergents did not affect the antigenicity of Thy-1.1, but only Lubrol-PX and deoxycholate gave effective solubilization as measured by activity remaining in the supernatant after centrifugation at 200000g for 40min. With Ag-B(4) antigen, Triton X-100, Triton X-67 and Nonidet P-40 gave effective solubilization as well as Lubrol-PX and deoxycholate. Solubilization of Thy-1.1 activity from leukaemia cells and a brain homogenate was also studied, but none of the non-ionic detergents gave satisfactory results with these tissues. 3. Extracts from thymocyte membranes were further examined by gel filtration and sucrose gradient centrifugation. The Thy-1.1 activity behaved as a single component in deoxycholate with a density similar to that of a globular protein, but in Lubrol-PX the antigen was contained in a low-density complex. In Lubrol-PX extracts Ag-B(4) was also found in aggregates not observed in deoxycholate. 4. The s(20,w) values for Thy-1.1 and Ag-B(4) antigens in deoxycholate were 2.4 and 4.4, and v values were 0.70 and 0.75 respectively. The Stokes radius observed for Thy-1.1 was 3.1nm and for Ag-B(4) 5.3nm. By using these values the molecular weights for the antigen-detergent complexes were calculated to be 28000 for Thy-1.1 and 100000 for Ag-B(4).
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PMID:Preliminary characterization of Thy-1.1 and Ag-B antigens from rat tissues solubilized in detergents. 421 84

Murine leukemia (Rauscher and Moloney strains) and sarcoma (Kirsten strain) virions, as well as the mammary tumor virus of mice, contain an RNA-dependent DNA polymerase. Optimal incorporation of deoxyribonucleoside triphosphates occurs at a critical detergent (Triton X-100) concentration (0.010-0.014%). At higher than optimal detergent concentrations the virion is seen to be disrupted and enzyme activity is lost. The virion, enzymatic activity, and newly synthesized DNA all cosediment in a sucrose gradient. Thus far the enzymatic activity has been found only in RNA viruses that have oncogenic properties.
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PMID:DNA synthesis by RNA-containing tumor viruses. 433 15

We examined the interaction of Abelson murine leukemia virus protein P120 with other cellular components after extraction with the nonionic detergent Triton X-100. Most of the Abelson murine leukemia virus P120-associated kinase activity was found in the detergent-insoluble matrix in both lymphoid and fibroblast cell lines. The P120 labeled during a short exposure of cells to [35S]-methionine was mainly in the detergent-insoluble matrix (lymphoid cells) or equally distributed in the detergent-insoluble matrix and the soluble fraction (fibroblasts). Steady-state-labeled P120 was distributed equally in the two fractions (lymphoid cells) or mostly in the soluble portion (fibroblasts). Thus, there was an apparent movement of P120 from the detergent-insoluble matrix to the detergent-soluble fraction and a concomitant loss of enzymatic activity. When the detergent-insoluble matrix was incubated with [32P]ATP in situ, phosphorylation of tyrosine residues of P120 was observed. We found an 80,000-molecular-weight fragment of P120 (designated F80) after extraction of fibroblast cells with detergent. F80 was not found in extracted lymphoid cells, but mixing labeled lymphoid cells and unlabeled fibroblasts before extraction produced the fragment. F80 contained the gag determinants of P120 but did not react with Abelson-specific serum. These data allowed us to assign various features of the protein to regions of the P120 molecule and to localize the Abelson-specific antigenic determinants to the C-terminal region of the molecule.
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PMID:Localization of the Abelson murine leukemia virus protein in a detergent-insoluble subcellular matrix: architecture of the protein. 617 95

Lactoperoxidase iodination and two-dimensional electrophoresis of the labeled proteins have demonstrated well-characterized cytoskeletal proteins (actin and tubulins) on the surface of human lymphocytes undergoing blastogenic transformation and of certain malignant human cells. Such proteins could not be detected on the surface of normal resting human lymphocytes. The most prominent cytoskeletal protein identified on the surface membrane of mitogen-transformed T and B lymphocytes was actin. In Epstein-Barr virus genome-positive Burkitt's lymphoma and lymphoblastoid cell lines and in two leukemia cells, the major iodinated membrane protein components were actin and alpha 1-, alpha 2-, and beta-tubulins. These proteins were firmly connected to the cytoplasmic skeleton and could not be removed by Triton X-100. Concurrent immunofluorescence studies with specific antibodies and F(ab')2 fragments confirmed the appearance of cytoskeletal components on the biochemical data, and indicated that such cytoskeletal proteins formed distinctive patterns on the cell surface, ranging from small patches to large projections. Five-hour labeling with [35S]methionine indicates that all such cells released large quantities of labeled actin and tubulins into the culture medium. These materials were not readsorbed to the membrane surfaces of the cells.
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PMID:Appearance of cytoskeletal components on the surface of leukemia cells and of lymphocytes transformed by mitogens and Epstein-Barr virus. 625 49

The gp52 glycoprotein of the spleen focus-forming virus found in the Friend and Rauscher complexes of murine leukemia viruses (MuLV) has been previously identified as a recombinant molecule involving substitutions and deletions of the MuLV env gene. Unlike the MuLV structural glycoproteins, gp52 is defective in its transport to the cell surface. We have studied aspects of the intracellular transport and membrane association of gp52 to investigate the possible mechanisms underlying the defective transport process. It was found that a panel of monoclonal antibodies to different epitopes of p 15E, as well as an antiserum to a synthetic peptide corresponding to the carboxy terminus of MuLV envelope precursors, failed to react with gp52. Despite the possible absence of membrane-anchoring regions of MuLV envelope proteins known to reside on p 15E, gp52 was not found to be secreted into the culture fluids. Detergent extraction studies indicated that gp52 is associated with the membranes and not the contents of microsomal vesicles in speen focus-forming virus-infected cells. gp65, the processed form of gp52, could be labeled with [3H]palmitic acid, suggesting a membrane association. To determine whether a spontaneous denaturation occurs leading to aggregation and defective transport of gp52, we studied the surface expression of gp52 in cells grown at different temperatures, as well as the solubility of gp52 in low concentrations of Triton X-100. No evidence of aggregation or of a temperature-dependent difference in transport was obtained. gp52 appears to be a monotopic integral membrane protein, unlike MuLV envelope proteins which are bitopic integral membrane proteins; proteolytic digestion of intact microsomal vesicles did not reveal a detectable cytoplasmic tail under conditions where this could be demonstrated on MuLV envelope precursors. We suggest that a loss of putative signals involved in mediating intracellular transport is a likely cause for the defective transport of the spleen focus-forming virus glycoproteins.
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PMID:Membrane association and defective transport of spleen focus-forming virus glycoproteins. 631 35

Rat basophil leukemia cell homogenates effectively catalyze the conversion of leukotriene A4 to a mixture of leukotrienes C4 and D4 in the presence of glutathione. These homogenates also catalyze the formation of adducts of halogenated nitrobenzene with glutathione, as determined spectrophotometrically. While all the classical glutathione S-transferase activity resides in the soluble fraction of the homogenates, the thiol ether leukotriene-generating activity is found in the particulate fraction. This "leukotriene C synthetase" activity has been solubilized from a crude high-speed particulate fraction by means of the nonionic detergent, Triton X-100. The solubilized enzyme is incapable of converting 2,4-dinitrochlorobenzene to a colored product in the presence of glutathione. Nor will it react with 3,4-dichloronitrobenzene. On the other hand, under optimal conditions, this enzyme preparation is capable of generating about 0.1 nmol leukotriene C mg protein-1 min-1 in a reaction which continues in linear fashion for at least 10 min. This dissociation in substrate specificity, as well as differences in the inhibition profile, distinguish the enzyme activity in the particulate fraction from rat basophil leukemia cell homogenates from the microsomal glutathione S-transferase which has been described in rat liver homogenates, suggesting that this "leukotriene C synthetase" is a new and unique enzyme.
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PMID:Solubilization and characterization of the leukotriene C4 synthetase of rat basophil leukemia cells: a novel, particulate glutathione S-transferase. 632 87

The cytosolic glutathione S-transferases of rat liver have been fractionated by chromatofocusing into 10 distinct fractions based on their reactivity with 2,4-dinitrochlorobenzene. All these fractions were capable of generating leukotriene C4 (LTC4) from leukotriene A4 (LTA4) to some extent. An inhibitor of leukotriene synthesis, U-60,257, inhibited the activity of these enzymes. The cytosolic glutathione S-transferases of rat basophil leukemia (RBL) cells have been similarly fractionated. U-60,257 inhibited the activity of some of these fractions but not that of others. None of the fractions of the enzyme from RBL cells formed LTC4 from LTA4. The microsomal glutathione S-transferase from rat liver also produced LTC4 from LTA4. It differs from the microsomal LTC synthetase of RBL cells in at least two respects: (1) The enzyme from RBL cells did not react with chromophoric substrates like dinitrochlorobenzene while the enzyme from liver did react. (2) Triton X-100 potentiated the activity of the enzyme from basophil leukemia cells and solubilized it, while it inhibited the activity of the leukotriene-synthesizing enzyme in the rat liver preparation. These results, along with a distinctly different inhibitor profile, indicate that LTC synthetase is a new and distinct glutathione S-transferase.
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PMID:Leukotriene C synthetase, a special glutathione S-transferase: properties of the enzyme and inhibitor studies with special reference to the mode of action of U-60,257, a selective inhibitor of leukotriene synthesis. 638 74

We evaluated protein expression in leukocytes from 20 patients with chronic lymphocytic leukemia (CLL), including one with the rare T-cell form of the disease. To identify proteins that potentially could be used to characterize leukemia or as candidates for new markers of differentiation, we studied cell and membrane extracts from these leukemic cells. We used immune precipitation and extraction of integral membrane proteins with Triton X-114 to identify known proteins on the surface of these cells. Extraction with Triton X-114 in the presence of protease inhibitors yielded reproducible membrane extracts, which we examined by two-dimensional gel electrophoresis. Of the approximately 2000 proteins or protein subunits so resolved from cell lysates and the 450 from membrane extracts of leukocytes from patients with T- and B-cell CLL, we were able to identify spots corresponding to the proteins designated by the OKT.4 and OKT.10 antibodies, the human class I and II histocompatibility antigens, beta 2-microglobulin, and surface IgM. We also defined sets of proteins that are characteristically expressed on the membranes of leukemic T or B cells, some of which correspond to previously defined markers of normal leukocyte subpopulations.
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PMID:Leukocyte membrane proteins in chronic lymphocytic leukemia, as studied by two-dimensional gel electrophoresis. 638 4

Leucocyte alkaline phosphatase (LAP) is a granulocyte enzyme whose concentration varies in disease states. In order to determine whether the pattern of expression is altered in leukaemic granulocytes, we have analysed the LAP isozyme pattern of a series of normal subjects and patients with various haematological diseases. Electrophoretic patterns of partially purified LAP samples were determined by polyacrylamide gel electrophoresis in the presence of Triton X-100. These patterns were reproducible on repeated samples from the same patient. Presence of the LAPf and LAPs isozymes were determined after staining with the dye Fast Blue BB. Granulocytes were obtained from 15 normal subjects. Thirteen of these samples had only the LAPs isozyme. The other two had LAPs, plus a small amount (less than or equal to 10% of total) of LAPf activity. Eight patients with stable phase chronic myelogenous leukaemia (CML) had only small amounts of the normal LAPs isozyme and no evidence of LAPf . Of 11 patients with CGL who clinically had blast crisis. 10 had both LAPs and LAPf . The eleventh patient who was Ph1 negative had only LAPs. Three of five patients with polycythaemia vera had only the LAPs isozyme while two had both isozymes. Six patients with non-malignant leucocytosis had only LAPs. We interpret this data to indicate that the increased levels of LAP activity in some CGL blast crisis patients are primarily related to synthesis of the LAPf isozyme.
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PMID:Altered isozyme patterns of leucocyte alkaline phosphatase in disease states. 658 2

The release of galactosyltransferase, sialyltransferase, and several glycosidase activities into the growth media from several normal and transformed cell lines was examined. Six of the seven cell lines released galactosyltransferase into their culture media. Only the human leukemia CCRF-CEM cells failed to release demonstrable galactosyltransferase activity. Release of galactosyltransferase activity into the media closely paralleled the growth curves for all but the BHKpy cells. These cells continued to release peak levels of galactosyltransferase activity into the culture media after their growth had plateaued. Media galactosyltransferase activity was unaffected by Triton X-100 treatment had remained in the supernatant fraction of a 100,000 X g, 12-hr centrifugation, suggesting that the cells release galactosyltransferase in a soluble form. In contrast to galactosyltransferase activity, only one of the cell lines (L1210) released sialyltransferase activity in appreciable amounts. Even this level of activity was 20-fold less than that observed for galactosyltransferase in the media from L1210 cells. Of the nine glycosidase activities assayed, only N-acetylglucosaminidase was observed in significant amounts in the media from all but the CCRF-CEM cells. However, N-acetylglucosaminidase release did not correlate closely with cell growth. These findings suggest a relatively specific release of galactosyltransferase and N-acetylglucosaminidase activities by cells in tissue culture. Moreover, the release of galactosyltransferase closely parallels cell growth. The significance of these released enzymes, especially to cell growth, has yet to be determined.
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PMID:Release of glycosyltransferase and glycosidase activities from normal and transformed cell lines. 678 58


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