Figure 5.

β₂AR did not couple to Gα_s or Gα_i to initiate the calcium response. a, treatment with the Gα_s CTX did not potentiate signaling with ISO. b, treatment with CTX significantly increased cytoplasmic cAMP (***, p = 0.0004). c, treatment with the Gα_i PTX did not suppress signaling with ISO. d, treatment with PTX completely eliminated changes in membrane potential induced by the dopamine-2 receptor upon the addition of dopamine (DA). Ca²⁺ and membrane potential traces represent three or more independent experiments, and error bars indicate internal replicate S.E. The bar graphs are the averages of three or more independent experiments, and the error bars indicate S.E. AU, absorbance units.