Source:http://linkedlifedata.com/resource/umls/id/C1517335
NCI: G-aS-coupled receptors stimulate adenylyl cyclase (AC), which synthesizes cAMP from ATP. In contrast Gai-coupled receptors inhibit AC and so reduce cAMP formation. The bg subunits from Gai and other G proteins are able to activate the MAP kinase pathways and PLCb. GPCRs coupled to the Gaq family of G proteins stimulate PLCb, which cleaves membrane phospholipids to produce IP3, which mobilizes intracellular calcium, and DAG, which activates PKC. Second messenger pathways then activate a range of effector systems to change cell behavior; in many cases this includes the regulation of gene transcription.