FIGURE 3.
RAMP2-mediated modulation of the GCGR is G protein-dependent. A and B, glucagon concentration-response curves in yeast strains containing either GPA1/Gαs (A) or GPA1/Gαi (B) chimeras expressing the GCGR in the presence of a vector control, RAMP1, or RAMP2. Activation of the reporter gene was calculated as a percentage of the maximum response observed in the absence of RAMP2. C and D, SPAs to determine Gαs (C) and Gαi (D) activation upon stimulation of cell membranes, containing the GCGR in the presence or absence of RAMP2, with increasing concentrations of glucagon. E, HEK-293 cells containing the GCGR and RAMP2 or a vector control were incubated with 200 ng/ml PTX or a vehicle control for 16 h before stimulation with glucagon and determination of cAMP accumulation. All values are the mean of at least three independent experiments ± S.E. (error bars).