ANIMAL PHYSIOLOGY
CHEMICAL SIGNALS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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it is used to activate protein kinases in the signal transduction pathway
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it is broken down by phosphodiesterase
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it is a g-protein coupled receptor
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it is formed by adenylyl cyclase
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Detailed explanation-1: -Adenylyl cyclase is a membrane-bound enzyme that catalyzes the conversion of ATP to cAMP. [1] cAMP, an intracellular second messenger, activates protein kinase A by dissociating its regulatory subunit from the catalytic subunit.
Detailed explanation-2: -Adenylyl cyclase is the only enzyme that produces cAMP, using low concentrations of Mg2+-ATP as substrate. It is a transmembrane enzyme, with most mass on the cytoplasmic side where G proteins interact. Cyclic guanosine monophosphate (cGMP) is a related second messenger that often antagonizes cAMP effects.
Detailed explanation-3: -As shown in Figure 22-2, adenylyl cyclase forms cAMP by creating a cyclic phosphodiester bond with the -phosphate group of ATP, with the concomitant release of pyrophosphate, which provides energy for the reaction.
Detailed explanation-4: -Adenylyl cyclase is the sole enzyme to synthesize cyclic AMP (cAMP), a key second messenger that regulates diverse physiological responses including sugar and lipid metabolism, olfaction, and cell growth and differentiation.