title: A fucose-deficient glycoprotein precursor to Rauscher leukemia virus gp69/71.
abstract: Rauscher leukemia virus glycoprotein gp69/71 is synthesized in virus-infected cells by way of a 90,000 dalton glycoprotein precursor, termed Pr2a+b. This precursor could be labeled with radioactive glucosamine and methionine but not with fucose; whereas gp69/71 could be detected by labeling with radioactive glucosamine, fucose, or a mixture of amino acids but seemed to be deficient in methionine relative to Pr2a+b. Pr2a+b and gp69/71, were specifically precipitated by an antiserum prepared against phosphocellulose purified Rauscher gp69/71. Other virus-specific precursors, in addition to Pr2a+b, could be precipitated by antiserum prepared against detergent disrupted virus. Neither Pr2a+b nor gp69/71 was precipitated from cell extracts by antisera to Rauscher p30. Tryptic maps of Pr2a+b and gp69/71 showed that these glycoproteins share many tryptic peptides. Pulse-chase experiments with 14C-labeled amino acids indicated that gp69/71 was not radio-labeled during the pulse-labeling period but slowly appeared during the chase incubations. Pr2a+b, however, was rapidly labeled and tended to disappear during long chases. Furthermore, two nonglycosylated viral proteins, termed p15E and p12E, are structurally related to Pr2a+b. Viral p15E and p12E contained the same methionine-containing tryptic peptide fraction as Pr2a+b as determined by ion-exchange chromatography. These results provide evidence that Pr2a+b is a precursor to gp69/71 and establish a structural and possible precursor-product relationship between Pr2a+b, p15E, and p12E.
mesh_terms: D000595:Amino Acid Sequence; D000956:Antigens, Viral / Q000032:analysis; D005643:Fucose / Q000032:analysis; D006023:Glycoproteins / Q000032:analysis* / Q000276:immunology; D008970:Molecular Weight; D011498:Protein Precursors / Q000032:analysis* / Q000096:biosynthesis / Q000276:immunology; D011925:Rauscher Virus / Q000032:analysis* / Q000276:immunology / Q000378:metabolism; D014764:Viral Proteins / Q000032:analysis* / Q000096:biosynthesis / Q000276:immunology
chemical_list: D000956:Antigens, Viral; D006023:Glycoproteins; D011498:Protein Precursors; D014764:Viral Proteins; D005643:Fucose