Immunological characterization of a low molecular weight polypeptide of murine leukemia virus

A low molecular weight polypeptide (MW 16,000) of the Rauscher strain of mouse leukemia virus (MuLV) has been isolated. A very sensitive and highly specific radioimmunoassay has been developed for its quantitation. The present studies indicate that this polypeptide is virus-coded and antigenically distinct from another virion protein, the group-specific (gs) antigen Different strains of MuLV contain antigens immunologically cross-reactive with the low molecular weight polypeptide. Studies are presented comparing the level of expression of this virion antigen in normal and transformed cells.