Selective Activation by Short Chain Alcohols of Glucagon Responsive Adenyl Cyclase in Liver
TL;DR: Alcohol produced a reversible activation of the glucagon responsive cyclase but did not activate the epinephrine responsive component, which further emphasizes the differences in the properties of the 2 hepatic cyclase systems.
Abstract: The effects of short chain alcohols (1 through 4 carbons) on hepatic cyclase were examined. Alcohol produced a reversible activation of the glucagon responsive cyclase but did not activate the epinephrine responsive component. The activation was accompanied by changes in the kinetic properties of the glucagon responsive cyclase and could not be explained in terms of enhanced Mg†† binding. These changes could reflect modifications of the solvent environment or binding of alcohol to a single site on the enzyme. The selective nature of this activation further emphasizes the differences in the properties of the 2 hepatic cyclase systems. (Endocrinology 87: 1075, 1970)
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TL;DR: The present review deals with various aspects of regulations, emphasizing the role of calcium/calmodulin in activating AC1 and AC8 in the central nervous system, the potential inhibitory effect of calcium on AC5 and AC6, and the changes in the expression pattern of the isoforms during development.
Abstract: At least nine closely related isoforms of adenylyl cyclases (ACs), the enzymes responsible for the synthesis of cyclic AMP (cAMP) from ATP, have been cloned and characterized in mammals. Depending on the properties and the relative levels of the isoforms expressed in a tissue or a cell type at a specific time, extracellular signals received through the G-protein-coupled receptors can be differentially integrated. The present review deals with various aspects of such regulations, emphasizing the role of calcium/calmodulin in activating AC1 and AC8 in the central nervous system, the potential inhibitory effect of calcium on AC5 and AC6, and the changes in the expression pattern of the isoforms during development. A particular emphasis is given to the role of cAMP during drug and ethanol dependency and to some experimental limitations (pitfalls in the interpretation of cellular transfection, scarcity of the invalidation models, existence of complex macromolecular structures, etc).
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TL;DR: This chapter discusses the role of phospholipids in transport and enzymic reactions, as the nonpolar environment can assist in binding and orientation of ligands, and influence the activity of water at the active site.
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TL;DR: Based upon the above observations, it is suggested that cyclic AMP may mediate the action of certain insulin-releasing agents whereas some other agents exert their insulinogenic action via mechanisms in which cyclicAMP may not be involved.
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