Description:
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Infection of JLS-V9 cells in culture with Rauscher murine leukemia virus induced the appearance on the cell surface of two classes of viral proteins: Rauscher murine leukemia virus gp70, and glycoproteins related to the viral core (
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) proteins with apparent molecular weights in sodium dodecyl sulfate polyacrylamide gels of 80 × 10
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and 95 × 10
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. The latter proteins were identified by lactoperoxidase-catalyzed iodination of the cell surface and by metabolic labeling with [
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H]mannose followed by immunoprecipitation with an antiserum directed against the major viral core protein, p30. Tryptic peptide maps of chloramine T-iodinated proteins indicated that 80 × 10
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- and 95 × 10
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-molecular-weight proteins were closely related. The 95 × 10
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-molecular-weight protein from Rauscher murine leukemia virus-infected cells had a tyrosine fingerprint which was identical to that of the 95 × 10
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-molecular-weight
<jats:italic>gag</jats:italic>
surface polyprotein of endogenous virus-producing AKR-A cells, suggesting that expression on the cell surface of glycosylated forms of
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precursor polyproteins may not be an exclusive property of leukemic thymocytes, but a more general phenomenon in murine leukemia virus infection. Tryptic fingerprint analysis of iodinated viral and cell-bound gp70's before and after desialylation indicated a lower level of glycosylation in the cell-bound gp70 population than in virions. Analysis of only surface-iodinated gp70 showed a simple pattern of exposed tryptic peptides which was very similar in Rauscher murine leukemia virus-infected cells and in AKR-A cells.
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