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)

The transforming gene product of the Abelson murine leukemia virus (A-MuLV) is a phosphoprotein encoded by combined viral and cellular sequences. Previous work has shown the existence of a serologically crossreactive normal cellular phosphoprotein called NCP150. We have utilized two-dimensional phosphopeptide mapping and phosphoamino acid analysis to compare the structures of NCP150 and wild-type and mutant forms of the A-MuLV protein labeled in vivo with 32P-orthophosphate. This analysis demonstrated clear homology between NCP150 and wild-type A-MuLV protein, but a number of phosphorylation differences were seen. Among them, two specific tyrosine phosphorylations present in all transformation-competent Abelson proteins were not observed in NCP150. No other phosphotyrosine-containing peptides were detected. In addition, transformation-defective mutants isolated from either the P120 or P160 wild-type strain lack phosphotyrosine-containing peptides. Double-infection studies with such transformation-defective and transformation-competent A-MuLV strains show that Abelson viral proteins may be substrates for their own tyrosine-specific kinase activity in vivo. These observations suggest that the phosphotyrosine kinase activity of the abl region may be controlled, and may function, differently in its viral and cellular forms.
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PMID:In vivo tyrosine phosphorylations of the Abelson virus transforming protein are absent in its normal cellular homolog. 618 33

The Abelson murine leukaemia virus protein (P120) can become phosphorylated in vitro by [gamma-32P]ATP. The protein has been purified from cell membranes to the point that in specific conditions virtually all of the incorporated 32P is in P120. The reaction is stimulated by Mn2+ and Mg2+ but not Ca2+ and is very rapid even at 0 degrees C. The phosphate is linked to P120 at tyrosine, a linkage not previously reported for a phosphorylation reaction. Phosphorylation may be involved in the transforming activity of viruses that cause leukaemia as well as sarcomas.
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PMID:Abelson murine leukaemia virus protein is phosphorylated in vitro to form phosphotyrosine. 624 93

Abelson murine leukemia virus (A-MuLV) is a replication-defective virus that transforms both fibroblasts and hematopoietic cells in vitro. The virus encodes a 120,000-molecular-weight protein (P120) that is composed of Moloney murine leukemia virus-derived gag gene sequences and A-MuLV--specific sequences. This protein is the only A-MuLV--encoded protein that has been detected, and thus P120 is a candidate for the transforming protein of A-MuLV. We now report isolation and characterization of three new A-MuLV isolates that do not synthesize P120 but do produce analogous proteins of larger (160,000 molecular weight) and smaller (100,000 and 90,000 molecular weight) size. All of these A-MuLV isolates transform fibroblasts and lymphoid cells in vitro. Because the different A-MuLV proteins vary in the A-MuLV--specific region of the molecule, these variants may set a maximum limit on the size of the A-MuLV transforming protein.
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PMID:Abelson murine leukemia virus mutants with alterations in the virus-specific P120 molecule. 624 37

Several transformation-defective (td) mutants of Abelson murine leukemia virus (AbLV) are described. Cells nonproductively infected with such mutants exhibited a high degree of growth contact inhibition, failed to form colonies in soft agar, lacked rescuable transforming virus, and were as susceptible as uninfected control cells to transformation by wild-type (wt) AbLV pseudotype virus. In addition, each of several td AbLV nonproductively infected cell clones analyzed was found to be nontumorigenic in vivo. Biochemical analysis of td mutant AbLV-infected clones revealed levels of expression of the major AbLV translational product, P120, and a highly related 80,000-Mr AbLV-encoded protein, P80, at concentrations analogous to those in wt AbLV-transformed cells. Although the AbLV-specific 120,000-Mr polyproteins expressed in td mutant AbLV-infected clones were indistinguishable from those in wt AbLV-transformed lines with respect to molecular weight and [35S]methionine tryptic peptide composition, they each differed from wt AbLV P120 in their patterns of post-translational phosphorylation. A previously described AbLV-associated protein kinase activity is shown to recognize as substrate a major tyrosine-specific acceptor site(s) contained within a single well-resolved tryptic peptide common to both AbLV P120 and P80. In vitro [gamma-32P]ATP-mediated labeling of this phosphorylation site was reduced to below detectable levels in td mutant nonproductively infected cell clones. These findings establish that the AbLV-encoded polyprotein P120 and its associated protein kinase activity are involved in AbLV tumorigenesis.
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PMID:Abelson murine leukemia virus transformation-defective mutants with impaired P120-associated protein kinase activity. 625 63

A previously described 120,000 dalton polyprotein, P120, encoded by the Abelson strain of murine leukemia virus (AbLV) is compared to translational products representing the entire Moloney murine leukemia virus (MuLV) genome. Each of three [35S]-methionine tryptic present in Moloney-MuLV Pr65gag are also represented in Pr180gag-pol. Of these, one peptide corresponding to Moloney-MuLV p12, but neither of two p30 specific peptides are present in AbLV P120. None of the twelve remaining methionine containing peptides present in AbLV P120 appear to correspond to those of either Moloney-MuLV Pr82env. AbLV P120 and a 110,000 dalton polyprotein encoded by a second transforming isolate of mouse origin, designated AK-T8, are both shown to be highly phosphorylated. Sites of phosphorylation included known phosphorylated structural (p12) components, as well as components encoded by acquired cellular sequences. Immunoprecipitates of AbLV P120 obtained from either cells or pseudotype virions are shown to contain protein kinase activity which recognizes AbLv P120 as substrate. This activity may represent an intrinsic property of the polyprotein itself or represent a cellular enzyme associated with AbLV P120 in the form of an enzyme-substrate complex.
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PMID:Abelson murine leukemia virus: characterization of a polyprotein containing phosphorylated component(s) encoded by newly acquired sequences. 625 63

Abelson murine leukemia virus transforms both lymphoid cells and fibroblasts in vitro and induces a unique type of thymus-dependent lymphoma in vivo. Four fibroblast-transforming strains of Abelson murine leukemia virus were identified, based on the sizes of the Abelson murine leukemia virus-specific phosphoproteins produced by these isolates. Two of these strains, the standard P120- and the P160-producing viruses, transformed lymphoid cells efficiently in vitro and induced Abelson disease in vivo. Two other strains, which synthesized small Abelson murine leukemia virus-specific proteins with molecular weights of 90,000 (P90) and 100,000 (P100), transformed lymphoid cells very poorly both in vitro and in vivo. The reduced oncogenic potentials of these isolates were correlated with a high level of synthesis of fairly unstable P90 and P100. In addition, neither P90 nor P100 functional efficiently in protein kinase assays. The correlation of abnormal metabolism and deficient protein kinase activity with the reduced oncogenic potentials of these virus strains supported a direct role for these proteins and the kinase activity in transformation. Furthermore, these results suggested that the requirements for lymphoid cell transformation and fibroblast transformation are different.
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PMID:Abelson murine leukemia virus mutants deficient in kinase activity and lymphoid cell transformation. 625 26

Abelson murine leukemia virus (A-MuLV)-transformed cells, simian virus 40 (SV40)-transformed cells, and chemically transformed cells all have increased levels of a 50,000-molecular-weight host cell protein. The protein was detected with sera raised to the A-MuLV-transformed and chemically transformed cells and was tightly bound to T-antigen in extracts of SV40-transformed cells. Partial protease digests showed that the proteins from all three sources were indistinguishable. The three proteins were phosphorylated in cells, and the linkage of phosphate to the A-MuLV-associated P50 was to a serine residue. By immunofluorescence methods, P50-related protein was found on the surface of both normal lymphoid cells and A-MuLV-transformed lymphoid cells, but cell fractionation showed that the majority of P50 was free in the cytoplasm of the transformed cells. Immunofluorescence also showed that P50 was found in granules in the cytoplasm of both untransformed and SV40-transformed fibroblasts. Other cells gave indistinct patterns. Cocapping experiments showed that the A-MuLV-specified P120 protein is weakly associated with the surface P50-related protein of lymphoid cells, but no association of P120 and P50 could be demonstrated by immunoprecipitation methods. Although a monoclonal antiserum to P50 was used in many of these studies, the identity of the bulk P50 protein with the molecules that are reactive at the cell surface requires further study.
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PMID:Increased concentration of an apparently identical cellular protein in cells transformed by either Abelson murine leukemia virus or other transforming agents. 626 7

The integrated Abelson murine leukemia virus (A-MuLV) genome cloned in bacteriophage lambda gtWES.lambda B was used to localize viral genetic sequences required for transformation. Comparison of the biological activity of cloned A-MuLV genomic and subgenomic fragments showed that subgenomic clones that lacked the 5' long terminal repeat and adjoining sequences (300 base pairs downstream of the repeat) were not biologically active. In contrast, subgenomic clones that lacked the 3' long terminal repeat and as much as 1.3 kilobase pairs of the A-MuLV cell-derived abl gene were as efficient as wild-type viral DNA in transformation. The A-MuLV-encoded polyprotein P120 and its associated protein kinase activity were detected in transformants obtained by transfection with Cla I, BamHI, and HindIII subgenomic clones. In contrast, individual transformants obtained with subgenomic Sal I clones expressed A-MuLV proteins ranging in size from 82,000 to 95,000 daltons. Each demonstrated an associated protein kinase activity. These results provide direct genetic evidence that only the proximal 40% of abl with its associated 5' helper viral sequences is required for fibroblast transformation.
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PMID:Abelson murine leukemia virus: structural requirements for transforming gene function. 629 Oct 48

A modification of the hydroxylamine cleavage of proteins is presented in which proteins were cleaved while immobilized in the matrix of a polyacrylamide gel. The reaction under these conditions retains its high specificity for Asn-Gly bonds and has the advantage that the gel matrix, acting as a carrier, facilitates simultaneous treatment of many samples, and contributes to a high recovery efficiency (60-90%) of the cleavage products. The cleavage is performed with individual protein bands excised from dried slab gels after detection by staining, autoradiography, or fluorography. The procedure can be easily combined with other techniques to further characterize the cleavage fragments. Also a two-dimensional version of the cleavage method was developed, which allows rapid recognition of interrelationships between proteins in a complicated mixture. The versatility of the procedure is demonstrated in a number of applications. Highly related strains of murine leukemia viruses were easily distinguished from one another by the unique cleavage patterns of their gag- and env-precursor polypeptides. Comparing the env-precursor gPr82env synthesized in the presence or absence of tunicamycin with its cell-free synthesized counterpart, revealed the presence of an amino-terminal signal sequence. Cleavage patterns of pro-opiomelanocortin (POMC) from three different species revealed a high degree of homology between rat and mouse POMC, whereas Xenopus POMC was very different. Regions to which carbohydrates are attached could be identified by comparing glycosylated and unglycosylated forms of POMC. Combining the hydroxylamine cleavage procedure with immunological characterization of the fragments showed a small but significant difference between the amino-terminal sequences of the recombinant transforming protein P120 of Abelson murine leukemia virus and of its parent molecule Pr65gag of Moloney murine leukemia virus.
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PMID:Hydroxylamine cleavage of proteins in polyacrylamide gels. 662 62

N-Methylisatin-beta-4',4'-diethylthiosemicarbazone (M-IBDET) and N-allylisatin-beta-4',4'-diallylthiosemicarbazone (A-IBDAT) selectively inhibited v-abl protein (P120), an oncogene product associated with tyrosine kinase activity. Concentrations of M-IBDET ranging between 0.17 and 0.64 microM and concentrations of A-IBDAT from 1.45 to 2.9 microM reduced tyrosine kinase activity significantly, whereas 0.64 microM M-IBDET and 2.9 microM A-IBDAT blocked P120 production. Cellular growth rate, protein production, and synthesis of p45 actin and p53 nuclear oncogene were not affected at these conditions. M-IBDET and A-IBDAT selectively suppress the v-abl oncogene as well as Moloney murine leukemia virus production.
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PMID:Selective repression of v-abl-encoded protein by N-methylisatin-beta-4',4'-diethylthiosemicarbazone and N-allylisatin-beta-4',4'-diallylthiosemicarbazone. 828 39


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