Molecular diversity of cyclic AMP signalling

Several neuroendocrine control systems are prominently controlled by G-prot ein coupled receptors that activate the cAMP signal transduction pathway. T he discovery of multiple genes that encode the molecular machinery of cAMP metabolism has revolutionized our knowledge of cAMP mediated processes. Thi s perhaps all too familiar second messenger can be generated by nine differ ent membrane enzymes in the context of varied levels of activation of G pro teins as well as Ca2+- and protein kinase C-dependent processes. The amplit ude, length and subcellular distribution of the cAMP signal are further mod ulated by over twenty functionally distinct isotypes of cAMP-degrading phos phodiesterases in a cell- and stimulus-specific manner. The present review summarizes the key properties of the molecular machinery that generates the cAMP signal and highlights how it is deployed in neuroendocrine systems. ( C) 2000 Academic Press.