Identification and characterization of a mouse mammary tumor virus protein uniquely expressed on the surface of BALB/cV mammary tumor cells

Virology. 1985 May;143(1):127-42. doi: 10.1016/0042-6822(85)90102-3.


A unique subline of BALB/c mice, designated BALB/cV, exhibits an intermediate mammary tumor incidence (47%) and harbors a distinct milk-transmitted mouse mammary tumor virus (MMTV). The BALB/cV subline was used to study the molecular basis of potential virus-host interactions involving cell surface-expressed MMTV proteins. Cell surface iodination identified virus-specific proteins expressed on BALB/cV primary mammary tumor cells grown in culture. In contrast to (C3H)MMTV-producing cell lines which expressed MMTV gp52, BALB/cV tumor cells lacked gp52 and expressed instead a 68K, env-related protein. The 68Kenv protein was also detected on the surface of metabolically labeled BALB/cV tumor cells by an external immunoprecipitation technique. The expression of 68Kenv was restricted to mammary tissues of BALB/cV mice that also expressed other MMTV proteins. Biochemical analysis established that 68Kenv was not modified by N-linked glycosylation. 125I-labeled 68Kenv was rapidly released into the media of tumor cell cultures and was recovered both in the form of a soluble protein and in a 100,000 g pellet. The biologic function of this cell surface-expressed viral protein remains unknown.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetylglucosaminidase
  • Animals
  • Cell Membrane / analysis
  • Electrophoresis, Polyacrylamide Gel
  • Immune Sera
  • Immunoenzyme Techniques
  • Mammary Neoplasms, Experimental / microbiology*
  • Mammary Tumor Virus, Mouse / metabolism*
  • Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase
  • Membrane Proteins / analysis*
  • Mice
  • Mice, Inbred BALB C
  • Molecular Weight
  • Viral Proteins / analysis*


  • Immune Sera
  • Membrane Proteins
  • Viral Proteins
  • Acetylglucosaminidase
  • Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase