title: Identification of a 36,000-molecular weight, gag-related phosphoprotein in lymphoma cells transformed by radiation leukemia virus.
abstract: Radiation leukemia virus (RadLV) causes thymic lymphoma in 90% of susceptible mice after a latent period of several months. The virally encoded polypeptides produced by RadLV-induced lymphoma cells were analyzed by immunoprecipitation and NaDodSO4/polyacrylamide gel electrophoresis. Along with the expected precursor and mature forms of gag and env gene products, a polypeptide of 36,000 molecular weight (p36) was precipitated by anti-gag antisera. It was not precipitable by normal sera or anti-env antibodies. Like the gag-associated fusion proteins of some acute leukemia viruses, p36 was found to be phosphorylated in vivo, although it lacked detectable ATP-specific protein kinase activity in vitro. By kinetics during pulse-chase labeling experiments and by comparison of two-dimensional tryptic peptide maps, this protein is not an intermediate in gag precursor processing. One lymphoma cell line is described that resembles a nonproducer RadLV-transformant, synthesizing relatively large amounts of p36 in the absence of Pr66gag or p30 production. Several RadLV-induced lymphoma cell lines also produce p36, while it was not detectable in the radiation-induced lines tested. In addition, p36 was not produced by mouse or mink fibroblasts or cultured thymocyte cell lines infected with virus passaged from the RadLV-induced lymphomas. We conclude that p36 may represent a previously unrecognized transformation-related protein induced directly or indirectly by infection with RadLV.
mesh_terms: D000818:Animals; D000956:Antigens, Viral / Q000276:immunology; D002460:Cell Line; D002472:Cell Transformation, Viral; D015683:Gene Products, gag; D009052:Leukemia Virus, Murine / Q000235:genetics / Q000276:immunology; D008223:Lymphoma / Q000209:etiology / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008907:Mink; D008970:Molecular Weight; D010750:Phosphoproteins; D014176:Protein Biosynthesis; D011494:Protein Kinases / Q000378:metabolism; D014764:Viral Proteins / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D000956:Antigens, Viral; D015683:Gene Products, gag; D010750:Phosphoproteins; D014764:Viral Proteins; D011494:Protein Kinases