Mammalian Membrane-bound Adenylyl Cyclases

Demonstration that the principal control of cellular cyclic AMP concentrations lies at the level of its synthesis has focused attention on adenylyl cyclase, the enzyme that catalyzes the conversion of intracellular ATP to cyclic AMP. The prototypical hormone-sensitive adenylyl cyclase system is comprised of three types of plasma membrane-associated components: heptahelical, G protein-coupled receptors for a variety of hormones, neurotransmitters, and autacoids; stimulatory and inhibitory heterotrimeric G proteins; and the catalytic entity itself.