Question

"Provided that cAMP levels are not influenced by factors other than G protein signaling, which hypothesis would be better supported if it was found that PT-mediated ADP ribosylation causes the smallest increases in cAMP concentration upon GCPR binding of ligand in cells containing the highest ratio of Gi to Gs protein-coupled receptors?"

Answer 1

Based on the hypothesis, an increase in the ratio of Gi to Gs proteins coordinated signalling, would decrease cAMP concentration when GCPR binds to it, with the Gi function intact and able to oppose the Gs protein activation.