Agonist-induced formation of unproductive receptor-G <sub>12</sub> complexes
Najeah Okashah, Shane C. Wright, Kouki Kawakami, Signe Mathiasen, Joris Zhou, Sumin Lu, Jonathan A. Javitch, Asuka Inoue, Michel Bouvier, Nevin A. Lambert
Abstract
Significance G protein-coupled receptors (GPCRs) are targeted by a large fraction of approved drugs and regulate many important cellular processes. Association of GPCRs with heterotrimeric G proteins in response to agonist activation is thought to invariably lead to G protein activation. We find instead that G 12 heterotrimers can associate with agonist-bound receptors in a manner that does not lead to activation. These unproductive agonist–receptor-G protein ternary complexes sequester G 12 heterotrimers and thus inhibit rather than support G 12 signaling. These findings reveal a mechanism whereby agonist activation of GPCRs can inhibit as well as promote G protein signaling.