Figure 6.

(A) Effect of Gβγ subunit expression on binding of [³H]bradykinin. Membranes of COS cells transfected with B₂ receptor alone or with B₂ receptor together with Gβ₁γ₇ were incubated for 1 h at 4°C with 5 nM [³H]bradykinin. At t = 0, GTPγS (1 μM) was added, and the cells were placed at 30°C. Specific high affinity binding of [³H]bradykinin was determined at the time points indicated. Data are from a representative experiment (triplicates ± SD) that was reproduced three times with similar results. (B) B₂ receptor-stimulated GTPγS binding. Membranes of B₂ receptor expressing HEK-293 cells (5 μg protein/50 μl) were incubated in the absence (B₂) or presence (B₂+Gβγ) of 50 nM Gβγ purified from bovine brain, and bradykinin-stimulated [³⁵S]GTPγS binding was determined at the time points indicated.