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)

Major virion low-molecular-weight polypeptides were isolated from the Moloney strain of murine leukemia virus (type C) by agarose chromatography in 6M guanidine hydrochloride and were shown to have molecular weights of 15,000 (p15), 12,000 (p12), and 10,000 (p10) by their elution volumes and by their relative mobilities in sodium dodecyl sulfate-polyacrylamide gels. Each polypeptide could be iodinated and employed in double antibody radioimmunoassay procedures. All three polypeptides demonstrated a high degree of type-specificity in serologic immunoprecipitation analysis and in corresponding competition immunoassays. The p15 was immunologically distinct from other viron polypeptides including p12 and p10; the p12 and p10 were highly related to each other but not to other virion polypeptides and were even more type-specific than the p15 in serologic tests. Competition immunoassays with p15 and p10 indicate that the Moloney strain of MuLV is only a distant relative of the Friend-Rauscher group. The combined use of the Kirsten and Moloney low-molecular-weight polypeptide immunoassays suggest that xenotropic viruses constitute yet another group(s) of murine leukemia virus with distinct type-specific antigens, further expanding an already heterogeneous group of mouse type C viruses.
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PMID:Serological studies with low-molecular-weight polypeptides from the Moloney strain of murine leukemia virus. 4 41

Cloned 3T3FL cells were synchronized in G1 phase of the cell cycle by deprivation of multiplication stimulatory activity of serum and were then infected with Moloney leukemia virus. Eclipse period of virus could be made to vary from less than 10 to 34 h. All virus release was completely dependent and occurred immediately after the first mitosis following serum reconstitution. Virus yield was not affected by the time of virus inoculation as related to the cell DNA synthetic phase. Colchicine arrested the cells in mitosis and prevented the formation of infectious virus. Viral proteins p10, p30, and gp71 were assayed in cell lysates during the growth curve of virus in synchronized cells. The group-specific determinants of each protein were measured in a competition radioimmunoassay. None of the virus proteins appeared during the eclipse period of the virus. All three proteins appeared simultaneously, coincident with mitosis, and continued to rise during the G1 phase. The absolute quantities of each protein were proportional to the amount of Moloney leukemia virus produced. The relative amounts of some of the viral proteins in the cell did not correspond to their content in purified virions suggesting several possible mechanisms of control.
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PMID:Mitosis is required for production of murine leukemia virus and structural proteins during de novo infection. 5 Apr 65

A polypeptide of molecular weight approximately 75,000 daltons, p(75), was identified on the surface of AKR spontaneous leukemia cells by lactoperoxidase-catalyzed radio-iodination. This protein was shown by immunoprecipitation to have antigenic determinants of MuLV p30, p15, and p10, but not gp70, suggesting that p(75) represents a polyprotein composed of virion core components. As evidenced by studies on incorporation of radioactive glucosamine, p(75) is probably glycosylated. No p(75) was found on 2 month old AKR thymocytes, and only a small amount of p(75) was detectable of thymocytes from 4 month old animals. However, substantial quantities of p(75) could be found on thymocytes from 6 month old, yet still preleukemic mice.
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PMID:A core polyprotein of murine leukemia virus on the surface of mouse leukemia cells. 6 4

Leukemic cells of AKR mice contain as constituents of their membranes the murine leukemia virus envelope protein gp70 and the precursor polyprotein of the viral internal (core) structural proteins. Both gp70 and the core polyprotein are represented on the cell surface as glycoproteins, as evidenced by incorporation of [3H]glucosamine into their structure and the binding of these proteins to lectins. The glycosylated core polyprotein exists in at least two serologically distinguishable forms: the 95,000-dalton polyprotein reacts with antisera prepared against the viral proteins p30, p12, and p10, whereas the 85,000-dalton polyprotein reacts with antisera prepared against the viral proteins p30 and p12, but not p10. Additional heterogeneity in these cell surface polyproteins has been observed wtih leukemias induced by exogenous leukemia viruses. Spontaneous leukemia cells of AKR mice invariably express gp70 and the core polyprotein on their cell surface; normal thymocytes of young AKR mice express gp70, but not the core polyprotein on their surface.
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PMID:Viral proteins expressed on the surface of murine leukemia cells. 6 23

Two species of glycosylated type C viral core polyprotein were identified on the surface of AKR spontaneous leukemia cells. One of these cell surface polyproteins was shown by immunoprecipitation to have antigenic determinants of murine leukemia virus p30, p15, p12, and p10; the other had murine leukemia virus p30, p15, and p12, but not p10, determinants. Both species were also expressed on thymocytes from 6-month-old, preleukemic AKR mice.
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PMID:Two species of type C viral core polyprotein on AKR mouse leukemia cells. 6 29

A thymic lymphoblastoid cell line derived from a New Zealand Black mouse produces murine leukemia virus (MuLV) and was used as a target in model systems for the in vitro study of antibody-dependent cellular cytotoxicity (ADCC). Several human lymphoblastoid cell lines were investigated as potential effector cells. The most promising (Raji cells) bound to antibody-coated target cells but caused only modest levels of ADCC at 25:1 effector-to-target cell ratio with substantial lysis in the absence of antiserum. Human peripheral lymphocytes were active as effector cells in ADCC at a 5:1 ratio and produced no lysis in the absence of antibody. These cells were used to demonstrate that high dilutions of rabbit antisera to MuLV antigens p30, p15, p12, and p10 were capable of mediating lysis of MuLV-producing target cells but not of a virus-negative murine cell line. A murine antiserum to Thy 1.2 and three caprine antisera to MuLV antigens that were active in complement-mediated cytotoxicity functioned poorly in inducing ADCC; however, rabbit antisera to similar antigens were 16- to 512-fold more efficient in cell-mediated than in complement lysis. The inefficiency of goat antisera was not due to shedding of cell surface antigens or generation of blocking factors but rather to lack of lytic interaction of antibody-coated targets with the effector cells.
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PMID:Antibody-dependent cellular cytotoxicity against murine leukemia viral antigens: studies with human lymphoblastoid cell lines and human peripheral lymphocytes as effector cells comparing rabbit, goat, and mouse antisera. 7 Apr 69

Cell membranes of Moloney lymphoma cells (YAC, of strain A origin) were solubilized by NP40. The antigenicity of the solubilized protein fraction was assayed by inhibition of the corresponding cytotoxic reaction against YAC target cells. The Moloney leukemia virus (MLV)-determined cell surface antigen (MCSA) was detected with mouse antisera, produced by the repeated inoculation of heavily irradiated YAC cells into syngeneic mice. Virion proteins gp71, p30, p15, p12 and p10 were identified with goat or rabbit antisera against purified Rauscher and Friend leukemia virus proteins. MCSA was found to bind to Con-A--Sepharose and was eluted by mannoside together with H-2A AND GP71. In contrast, p30, p12, p10 and part of p15 and p15(E), were not retained on the column and could be separated from MCSA. Passage of the glycoprotein fraction through Sephadex G-200 led to the separation of MCSA activity from gp71 and H-2A. MCSA eluted between the immunoglobulin (IgG) and the bovine serum albumin (BSA) size markers. MCSA could be also separated from the known viral proteins and from H-2 by velocity centrifugation in sucrose gradients. It sedimented with approximately 6.6 S ahead of gp71 (4.4 S) and H-2 (3.2 S). It is suggested that MCSA may be a glycoprotein with an approximate molecular weight of 110,000 and distinct from the known viral proteins gp71, p30, p15(E), p12, p10 and from H-2.
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PMID:Separation of the Moloney leukemia virus-determined cell surface antigen (MCSA) from known virion proteins associated with the cell membrane. 7 Dec 77

Murine leukemia viruses, such as Rauscher leukemia virus (RLV), contain a proteolytic factor which becomes activated after detergent treatment of the virus. This factor specifically cleaves P70, the gag precursor polyprotein which is enriched for in preparations of immature virus core subparticles. The factor has been partially purified on Sephadex G-75 columns. It has a molecular weight of 10,000-12,000 daltons but does not coincide in elution position with the major peaks of the viral polypeptides p10 or p12. Under optimal conditions, that is 2% NP-40 (v/v), 10 mM DTT, (pH 7.2) and incubation for 16 hr at 22 degrees C, cleavage of labeled P70 occurs and increasing amounts of the four gag polypeptides p30, p15, p12 and p10 are obtained. The P70 cleavage activity is blocked by TLCK, TAME, CBZ-lysine and other lysyl-containing protease inhibitors. Further, the CBZ-lysine inhibition is reversible, while an inhibition by phenyl-methylsulfonyl fluoride (PMSF) is irreversible. These inhibition studies suggest that a similarity exists between the P70 proteolytic factor and some serine proteases, such as trypsin. The cleavage pattern of P70-rich immature cores treated with trypsin or chymotrypsin is different from that obtained with the P70 proteolytic factor. Thus murine leukemia virions apparently contain a unique, highly specific protease which is present in small amounts and cleaves P70.
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PMID:Properties of a P70 proteolytic factor of murine leukemia viruses. 7 13

An experimental procedure for detecting and characterizing tumor-associated, virion, and histocompatibility antigens has been developed. The method takes advantage of the high resolution that proteins, solubilized by Triton X-100 and reduced, display after sodium dodecyl sulfate gel electrophoresis. The antigens can be detected as distinct molecular weight species by a highly sensitive inhibition of cytotoxic reaction. When coupled to the lactoperoxidase-catalyzed iodination of intact cells, the procedure permits the determination of externally exposed antigens. In the present study, the method has been applied to the Moloney leukemia virus-induced YAC lymphoma cells of strain A mice, which express a Moloney leukemia virus-determined cell surface antigen (MCSA) in addition to the type C viral proteins gp71, p30, p15, p15(E), p12, and p10. MCSA was identified as an exposed surface protein distinct in size and antigenic determinants from the major envelope and core protein of Moloney leukemia virus and the histocompatibility antigens. Multiple molecular weight species possessing antigenic determinants for MCSA, gp71, and H-2(a) have been detected. These results provide direct confirmation that MCSA is unrelated to the known virion structural proteins or to the H-2(a) antigen. This method should permit the direct identification and molecular weight characterization of any antigen whose determinants are not solely dependent on a complex quaternary structure and for which serological reagents are available.
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PMID:Moloney leukemia virus-induced cell surface antigen: detection and characterization in sodium dodecyl sulfate gels. 7 31

The expression of murine leukemia virus structural polypeptides on the surface of cells producing exogenous Friend leukemia virus, endogenous ecotropic AKR and xenotropic BALB/c virus was investigated. Antisera to Friend virus gp71, p30, p15E, p12 and p10 were employed in a complement-dependent chromium release assay and to immunoprecipitate lactoperoxidase iodinated surface polypeptides prior to analysis in polyacrylamide gel electrophoresis. With the latter technique gag-gene encoded proteins and their precursors were not discovered on the viral and cellular surface membranes. Only env-gene encoded polypeptides gp85, gp71, and p15E were detectable. p15E is embedded into the lipid membrane. gp85 is formed by disulfide linkage of p15E to surface-exposed gp71. The ratio of gp71 to gp85 is variable and apparently determined by the host cell. Antibodies of strong cytotoxicity are those against type- and group-specific epitopes of gp71 as well as type-specific epitopes of p12.
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PMID:Surface expression of murine leukemia virus structural polypeptides on host cells and the virion. 8 Nov 84


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