title: Origin of the minor glycoproteins of murine leukemia viruses.
abstract: Polyacrylamide gel electrophoretic analysis and immunoprecipitation were used to study glycoproteins from purified Rauscher murine leukemia virus (R-MuLV) and from AKR thymic lymphoblastoid cell membranes. In addition to gp70, a minor glycoprotein of approximately 52,000 daltons (gp52) was demonstrated in purified R-MuLV preparations, which was antigenically related to gp70. Analysis of R-MuLV glycopeptides obtained after exhaustive Pronase digestion showed that gp70 has at least two different glycopeptide size classes with molecular weights of 5,100 and 2,900, respectively. gp52, however, contained only a single glycopeptide size class of approximately 5,100 daltons, indicating that the two glycoproteins contain distinct carbohydrate components. Trypsin treatment of R-MuLV converted gp70 into a product with a molecular mass of approximately 52,000 daltons as well as a 45,000-dalton minor product, with little effect on virus infectivity. Similarly, trypsin treatment of 125I-labeled glycoproteins derived from AKR mouse lymphoblastoid cell membranes generated fragments antigenically related to gp70 and similar in size to those obtained by trypsin treatment of R-MuLV. In both cases, the appearance of cleavage products was accompanied by a decrease in gp70 during trypsin treatment. The occurrence of glycosylated components antigenically related to gp70 in AKR membrane glycoprotein preparations and in purified R-MuLV preparations which were similar to those generated by trypsin treatment supports the concept that these minor components arise from proteolytic cleavage of gp70.
mesh_terms: D002460:Cell Line; D002462:Cell Membrane / Q000032:analysis; D006020:Glycopeptides / Q000032:analysis; D006023:Glycoproteins / Q000032:analysis*; D008970:Molecular Weight; D009363:Neoplasm Proteins / Q000032:analysis*; D009374:Neoplasms, Experimental; D011925:Rauscher Virus / Q000032:analysis* / Q000187:drug effects; D014357:Trypsin / Q000494:pharmacology; D014764:Viral Proteins / Q000032:analysis*
chemical_list: D006020:Glycopeptides; D006023:Glycoproteins; D009363:Neoplasm Proteins; D014764:Viral Proteins; D014357:Trypsin