Figure 1. G Protein-Coupled Receptor (GPCR) Activation.

Generalized schematic for GPCR activation. Upon ligand binding to the GPCR, the receptor undergoes a conformational change whereby the α subunit of its associated G protein is activated by exchanging bound GDP for GTP. The α and βγ subunits of the G protein subsequently dissociate to activate their respective downstream signaling cascades. For a more comprehensive overview of the complex variety of GPCR signaling cascades, please refer to Neves et al.¹⁴⁸.

Abbreviations: PKA, protein kinase A; PYK, protein-rich tyrosine kinase; MEK5, Mitogen/extracellular signal regulated kinase kinase-5; PI3K, phosphatidylinositol-3 kinase; GRK, G protein-coupled receptor kinase; GIRK, G protein-activated inward rectifying K⁺ channel).