Answer to Pharmacology MCQ 450

The Correct option is D

The G protein is inactive when bound to GDP. When the G protein binds to the receptor, the G protein then releases the attached GDP, which is replace by a GTP from the cytosol, and becomes activated.

cAMP as a second messanger. cAMP is made from ATP by the enzyme adenylate cyclase. CAMP is broken down by phosphodiesterase (PDE). The activity of adenylate cyclase can be modulated in by G-proteins. When stimulatory agonists (As)bind with their receptors the stimulate G-proteins of the Gs class. This increases adenylate cyclase activity and cAMP levels. When inhibitory agonixts (Ai)bind with their receptors the stimulate G-proteins of the Gi class. This decreases adenylate cyclase activity and cAMP levels.

Category: Pharmacology MCQs