Stimulation and inhibition of adenylyl cyclase

The adenylyl cyclase serves as a signal transduction system located in the plasma membrane of apparently every cell type of higher organisms. It generates the second messenger cyclic AMP, which plays an important regulatory role in many diverse biological processes such as glycogenolysis and lipolysis, cardiac inotropy and chronotropy, vascular tone, neurotransmitter and hormone release in neuronal and endocrine cells, respectively, and cell growth. Cyclic AMP acts by activating cyclic AMP-dependent protein kinases which phosphorylate various ubiquitous and cell-specific proteins, which covalent modifications cause the final cellular responses. The complete adenylyl cyclase signal transduction system is a multi-component system consisting of various receptors which recognize the extracellular signals, two guanine nucleotide-binding regulatory proteins (G-proteins) which transduce the signals from the receptors to the adenylyl cyclase and the effector enzyme which catalyzes the formation of cyclic AMP from ATP. This brief review focusses on our current knowledge about structure and function of the components involved in the stimulation and inhibition of adenylyl cyclase and provides some recent data on possible modifications of these components.