FIG. 7.

Lack of phosphorylation of native BLV Env protein in B-lymphoid cells. BLV-producing BL3* cells and BLV-negative BL3 cells were incubated with [³⁵S]Met/Cys or [³²P]orthophosphate for 3 to 4 h. After lysates were prepared in the presence of NEM, Env proteins were immunoprecipitated using monoclonal antibodies specific for the D epitope of SU. Samples were treated with 2-mercaptoethanol and heated before proteins were separated by SDS-PAGE. Molecular mass standards are shown at left, and locations of the Env precursor protein (gPr72), SU (gp51), and TM (gp30) are shown at right.