Prostaglandin F2α and angiotensin II type 1 receptors exhibit differential cognate G protein coupling regulation

• Published in: The Journal of biological chemistry Vol. 298; no. 9; p. 102294
• Main Authors: Sedki, Dana, Cho, Aaron, Cao, Yubo, Nikolajev, Ljiljana, Atmuri, N. D. Prasad, Lubell, William D., Laporte, Stéphane A.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01-09-2022; American Society for Biochemistry and Molecular Biology
• Subjects: angiotensin II type I receptor; BRET; G protein–coupled receptor; prostaglandin F2α receptor; signaling; BRET; Q/D-Gαq; angiotensin II type I receptor; B2R; signaling; ROCK; prostaglandin F2α receptor; PGF2α; AT1R; FP; MAPK; PDC; BSA; HEK293; TPα; YM; GPCR; G protein–coupled receptor; AngII
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/j.jbc.2022.102294

Promiscuous G protein–coupled receptors (GPCRs) engage multiple Gα subtypes with different efficacies to propagate signals in cells. A mechanistic understanding of Gα selectivity by GPCRs is critical for therapeutic design, since signaling can be restrained by ligand–receptor complexes to preferentially engage specific G proteins. However, details of GPCR selectivity are unresolved. Here, we investigated cognate G protein selectivity using the prototypical promiscuous Gαq/11 and Gα12/13 coupling receptors, angiotensin II type I receptor (AT1R) and prostaglandin F2α receptor (FP), bioluminescence resonance energy transfer–based G protein and pathway-selective sensors, and G protein knockout cells. We determined that competition between G proteins for receptor binding occurred in a receptor- and G protein–specific manner for AT1R and FP but not for other receptors tested. In addition, we show that while Gα12/13 competes with Gαq/11 for AT1R coupling, the opposite occurs for FP, and Gαq-mediated signaling regulated G protein coupling only at AT1R. In cells, the functional modulation of biased ligands at FP and AT1R was contingent upon cognate Gα availability. The efficacy of AT1R-biased ligands, which poorly signal through Gαq/11, increased in the absence of Gα12/13. Finally, we show that a positive allosteric modulator of Gαq/11 signaling that also allosterically decreases FP–Gα12/13 coupling, lost its negative modulation in the absence of Gαq/11 coupling to FP. Together, our findings suggest that despite preferential binding of similar subsets of G proteins, GPCRs follow distinct selectivity rules, which may contribute to the regulation of ligand-mediated G protein bias of AT1R and FP.