Structural features of heterotrimeric G-protein-coupled receptors and their modulatory proteins

Over the past 20 years, the general mechanism for signaling through 7-trans membrane helix receptors coupled to GTP hydrolysis has been worked out. Alt hough similar in overall organization, subtype variability and subcellular localization of components have built in considerable signaling specificity . Atomic resolution structures for many of the components have delineated t he domain organization of these complex proteins and have given physical fo rm to the idea of subtype specificity This review describes what is known a bout the physical structures of the 7-transmembrane helix receptors, the he terotrimeric GTP binding coupling proteins, the adenylate cyclase and phosp holipase C effector proteins, and signaling modulatory proteins, such as ar restin, phosducin, recoverin-type myristoyl switch proteins, and the plecks trin homology domain of G-protein receptor kinase-2. These images allow exp erimenters to contemplate the details of the supramolecular organization of the multiprotein complexes involved in the transmission of signals across the cellular lipid bilayer.