FIG. 2.

Detection of Rex-2 mutants in 293 T cells. 293 T cells were transfected with 25 μg of wild-type (Wt) or various rex mutant expression vectors or vector alone (control). At 24 h posttransfection, cells were metabolically labeled using [³⁵S]methionine-[³⁵S]cysteine; cell lysates were made as described in Materials and Methods. Lysates were immunoprecipitated using anti-Rex antiserum in the presence of protein A-Sepharose. Immunoprecipitated proteins were fractionated by SDS-PAGE and visualized by autoradiography. ¹⁴C low-molecular-mass markers are indicated on the left (lane M). The results indicate that all of the Rex mutants are efficiently expressed in 293 T cells. p26^rex and p24^rex were quantitated by PhosphorImager analysis over four independent experiments, and values were averaged. The p26^rex/p24^rex ratio is presented below each lane. (Note that M17 displays a significant reproducible reduction in the level of p26^rex.)