Fig. 3
Major G protein-coupled receptor (GPCR) signaling pathways. GPCR signaling is transduced through several canonical or noncanonical pathways that ultimately proceed through second messengers. The Gs and Gi pathways converge on AC to modulate intracellular cAMP; the Gq pathway increases intracellular Ca2+ and MAPK and PI3K/Akt signals by activating PLC; the β-arrestin/GRK pathway activates downstream MAPK and PI3K/Akt signals. AC adenylyl cyclase, ATP adenosine triphosphate, cAMP cyclic adenosine monophosphate, PKA protein kinase A, PLC phospholipase C, PIP2 phosphatidylinositol 4,5-bisphosphate, IP3 inositol trisphosphate, DAG diacylglycerol, PKC protein kinase C, MAPK mitogen-activated protein kinase, PI3K phosphoinositide-3-kinase, Akt serine-threonine protein kinase, GRK G protein-coupled receptor kinase
