AP BIOLOGY

Detailed explanation-1: -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-2: -cAMP is a nucleotide synthesised within the cell from ATP by the action of a membrane-bound enzyme, adenylyl cyclase. It is produced continuously and inactivated by hydrolysis to 5′-AMP by the action of a family of enzymes known as phosphodiesterases (PDEs).

Detailed explanation-3: -cAMP is synthesized from ATP by the enzyme adenylyl cyclase with the release of pyrophosphate and hydrolyzed into 5′-AMP by the enzyme phosphodiesterase.

Detailed explanation-4: -Cyclic AMP is the most ubiquitous second messenger used from single-cell organisms to mammalian cells and tissues. cAMP synthesis is catalyzed by the enzyme adenylyl cyclase (AC), which has been shown to be encoded by several genes.

Detailed explanation-5: -In the brain, as in other tissues, adenylyl cyclases can be activated by receptor-coupled stimulatory Gs proteins. For example, noradrenergic neurons of the locus ceruleus project to pyramidal neurons of the hippocampus and activate adenylyl cyclase through Gs protein-coupled -adrenergic receptors (FIGURE 1).