Figure 3.

Hormone-stimulated production of inositol trisphosphate in 293 cells expressing RGS proteins. (A) Inositol trisphosphate accumulation was determined after cells were treated for 15 sec with varying concentrations of bradykinin. Expression of MycRGS4 (▪) markedly attenuated the bradykinin response at all concentrations of hormone tested relative to control cells (○); the effect of NH₆GAIP (•) was apparent only at lower concentrations. (B) Time course of inositol trisphosphate production by cells treated with 100 nM bradykinin (○, control cells) reveals a more prominent inhibition of the response in cells expressing MycRGS4 (▪) than in those expressing NH₆GAIP (•). The data represent the mean of triplicates ± SD. Three independent experiments yielded similar results.