Distribution of Viral Glycoprotein Gp 69/71 on Cell Surfaces of Producer and Nonproducer Cells

The distribution of the viral glycoprotein, gp 69/71, was studied on the cell surfaces of virus-producing and nonproducing cells. gp 69/71 was distributed evenly on cell membranes and on viral membranes of cells producing murine leukemia virus. gp 69/71 was distributed uniformly on cell membranes of thymocytes from NZB and strain 129 mice but was not detected on cell membranes of BALB/c thymocytes. Viral particles were associated with NZB and BALB/c thymocytes but were not in or on 129 thymocytes. We conclude that the presence of gp 69/71 on thymocyte membranes is not related to virus production. In the strains showing gp 69/71 on their thymocyte surfaces (NZB and 129), a large percentage of the thymocytes are positively labeled, all more or less equally. Immunochemical analysis of cell surface proteins labeled with 125I corroborated the ultrastructural observations. Thus, gp 69/71 can be expressed on the surface of thymocytes independently of virus particle production.