G Protein Signaling : Humana Press : 9781588291370 : 1588291375 : 15 Sep 2003 : Since the initial discovery of the G protein-coupled receptor system that regulates cyclicAMP production, the G protein field has rapidly expanded. Cell surface receptors that couple to heterotrimeric G proteins, the G prote- coupled receptors (GPCRs), number in the hundreds and bind to a wide div- sity of ligands including, biogenic amines (e. g. , adrenaline), lipid derivatives (e. g. , lysophosphatidic acid), peptides (e. g. , opioid peptides), proteins (e. g. , thyroid-stimulating hormone), and odorants to name a few. The GPCR system is found throughout biology in such simple organisms as yeast and in such more complex organisms as Dictyostelium discoideum (slime mold), Caen- habditis elegans (nematode worm), and of course in humans. GPCRs and their associated G protein systems are the subject of intense academic research and because of their involvement in a human biology and disease, the pharmac- tica