G-protein-coupled receptors (GPCRs) are increasingly recognized to operate from intracellular membranes as well as the plasma membrane. The β 2 -adrenergic GPCR can activate G s -linked cyclic AMP (G s -cAMP) signaling from endosomes. We show here that the homologous human β 1 -adrenergic receptor initiates an internal G s -cAMP signal from the Golgi apparatus. By developing a chemical method to acutely squelch G-protein coupling at defined membrane locations, we demonstrate that Golgi activation contributes significantly to the overall cellular cAMP response. Golgi signaling utilizes a preexisting receptor pool rather than receptors delivered from the cell surface, requiring separate access of extracellular ligands. Epinephrine, a hydrophilic endogenous ligand, accesses the Golgi-localized receptor pool by facilitated transport requiring the organic cation transporter 3 (OCT3), whereas drugs can access the Golgi pool by passive diffusion according to hydrophobicity. We demonstrate marked differences, among both agonist and antagonist drugs, in Golgi-localized receptor access and show that β-blocker drugs currently used in the clinic differ markedly in ability to antagonize the Golgi signal. We propose 'location bias' as a new principle for achieving functional selectivity of GPCR-directed drug action.
Recommended CitationIrannejad, Roshanak; Pessino, Veronica; Mika, Delphine; Huang, Bo; Wedegaertner, Philip B.; Conti, Marco; and von Zastrow, Mark, "Functional selectivity of GPCR-directed drug action through location bias." (2017). Department of Biochemistry and Molecular Biology Faculty Papers. Paper 141.