AP BIOLOGY

Detailed explanation-1: -The free Gs subunit stimulates the enzyme adenylyl cyclase (AC) to catalyze the cyclization of ATP to generate cAMP and pyrophosphate (5, 6).

Detailed explanation-2: -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-3: -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-4: -In T cells, the cAMP level is controlled by two types of enzymes: ACs and phosphodiesterases (PDE). ACs catalyze the production of cAMP from ATP, whereas PDEs control the rate of cAMP degradation to AMP.

Detailed explanation-5: -Studies of chemical mechanisms in adenylyl cyclases (AC) are justified by an importance of the enzyme-catalyzed conversion of adenosine triphosphate (ATP) to cyclic adenosine monophosphate (cAMP).