For each of the following sentences, select the best word or phrase from the list below to fill in the blanks.Not all words or phrases will be used; each word or phrase should be used only once. adenylyl cyclase AMP ATP ATPase Ca2+ cAMP cholera toxin diacylglycerol five four GDP GTP GTPase phosphodiesterase seven three twelve two
G-protein-coupled receptors (GPCRs) all have a similar structure with __________ transmembrane domains.When a GPCR binds an extracellular signal, an intracellular G protein, composed of __________ subunits, becomes activated.__________ of the G-protein subunits are tethered to the plasma membrane by short lipid tails.When unstimulated, the α subunit is bound to __________ which is exchanged for __________ on stimulation.The __________ activity of the α subunit is important for inactivating the G protein.__________ inhibits this activity of the α subunit, thereby keeping the subunit in an active state.