摘要：

This chapter introduces glucagon-sensitive adenyl cyclase as a model for receptors in plasma membranes. Hormone-sensitive adenyl cyclase systems are located principally, if not exclusively, in the surface membrane of the cell. Isolated fat cells contain in their surface membrane an adenyl cyclase, which is activated by catecholamines, five different peptide hormones, and fluoride. The study of hormone-sensitive adenyl cyclase systems offers certain advantages as a model for all types of receptors, such as hormone receptors other than adenyl cyclase, drug receptors, and neurotransmitter receptors. With an adenyl cyclase system, the consequence of events occurring at the receptor may be observed directly by following the production of cyclic AMP rather than by following some functional parameter such as muscle contraction, which is at least several steps removed from the receptor and is, therefore, subject to other control mechanisms. The chapter presents the status of one such system, the glucagon-sensitive adenyl cyclase from liver plasma membranes. Information obtained from other adenyl cyclase systems is presented only to expand the general significance of the liver system.

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