The mouse mammary tumor virus long terminal repeat encodes a 47 kDa glycoprotein with a short half-life in mammalian cells.
The mouse mammary tumor virus proviral DNA contains an open reading frame in the 3' long terminal repeat which can code for a 36 kDa polypeptide with a putative transmembrane sequence and five N-linked glycosylation sites. This gene is known to code for a superantigen which deletes a specific subset of CD4+ T lymphocytes in vivo. The superantigen encoded by the exogenous mouse mammary tumor virus of the GR strain acts specifically on V beta 14 bearing T cells. We produced recombinant vaccinia viruses to express either the complete or a truncated ORF protein after infection of primate cells in culture. The complete ORF gene in mammalian cells leads to the production of a 47 kDa protein which is specifically detected with an anti-ORF-peptide antiserum. The 47 kDa protein can be labeled with D-[2-3H]mannose and its synthesis is inhibited by tunicamycin, an N-linked glycosylation inhibitor, indicating that it is a glycoprotein. The truncated ORF protein beginning at the second ATG of the open reading frame is also modified, but the C-terminal half of ORF, starting at the fifth ATG, has the expected size of the non modified polypeptide. Pulse-chase experiments indicate that the ORF protein has a short half-life of about 1.5-2 hr.
Krummenacher
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C
Institute for Microbiology, University of Lausanne, Switzerland.
Diggelmann
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H
D000818:Animals; D002478:Cells, Cultured; D006023:Glycoproteins / Q000096:biosynthesis* / Q000235:genetics; D006031:Glycosylation / Q000187:drug effects; D006207:Half-Life; D008324:Mammary Tumor Virus, Mouse / Q000235:genetics*; D008358:Mannose / Q000378:metabolism; D016366:Open Reading Frames; D011323:Primates; D011994:Recombinant Proteins / Q000096:biosynthesis; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D017384:Sequence Deletion; D018089:Superantigens / Q000096:biosynthesis* / Q000235:genetics; D014415:Tunicamycin / Q000494:pharmacology; D014616:Vaccinia virus / Q000235:genetics; D014764:Viral Proteins / Q000096:biosynthesis* / Q000235:genetics
D006023:Glycoproteins; D011994:Recombinant Proteins; D018089:Superantigens; D014764:Viral Proteins; C083524:mouse mammary tumor virus protein gp47; D014415:Tunicamycin; D008358:Mannose