Figure 1.

Expression of RGS proteins in stably transfected 293 cell clones. (A) Whole-cell lysates of transfected cells were analyzed by Western immunoblotting. Cells were transfected with empty expression vector or vector including NH₆GAIP or MycRGS4. Expression of NH₆GAIP was detected with a GAIP-reactive antiserum (R381, Left) and MycRGS4 with the Myc-reactive antibody (Anti-Myc, Right). Numbers at the left represent the migration position of prestained molecular mass standards in kilodaltons. (B) Homogenates of cells transfected with the empty vector or with vector encoding NH₆GAIP or MycRGS4 were assayed for GAP activity with [γ-³²P]GTP bound to purified α_i1 as substrate. The bars represent the mean ± the SD of samples assayed in triplicate. Three independent clones of cells expressing NH₆GAIP or MycRGS4 gave qualitatively similar results.