FIG. 2.
Expression and release of serine mutants. COS-1 cells were metabolically labeled for 2.5 h with [35S]methionine 48 h after transfection with the indicated mutants. Gag proteins were immunoprecipitated from cell and medium lysates with polyclonal anti-RSV serum, resolved by SDS-PAGE, and visualized by fluorography. Positions of molecular size markers are indicated on the right. The positions of the full-length Gag protein (Pr76gag) and those of its mature cleavage products are indicated on the left. The heterogeneous MA proteins are marked by larger brackets. Myr0 and dMA4 are wild-type and negative controls, respectively.