Figure 2.

Effect of a Gβ₃ mutant (amino acids 45–340) on basal, AlF₄⁻-, UTP-, and bradykinin-stimulated inositol phosphate levels. (A) Immunoblot of COS cells transfected with the Gβ₃ mutant (β₃mut) or with wild-type Gβ₃ (WT). Gγ₁ and Gγ₇ were cotransfected as indicated. As a control, mock-transfected COS cells were used (-). (B–E) Inositol phosphate levels of COS cells expressing the Gβ₃ mutant (β₃mut) together with Gγ_1,7 or wild-type Gβ₃ (WT) with Gγ₇. In B, basal inositol phosphate levels were determined. The increase in inositol phosphate levels over the respective basal levels after stimulation by AlF₄⁻ (300 μM AlCl₃/10 mM NaF), by UTP (100 μM), and by bradykinin (100 nM) are given in C, D, and E, respectively. Data are from a representative experiment (triplicates ± SD) that was reproduced three times with similar results.