What is the role of phosphodiesterase in relation to cAMP?

• A. It amplifies the signal of cAMP.
• B. It converts cAMP back to ATP.
• C. It breaks down cAMP to regulate the response.
• D. It activates Adenylate Cyclase.

Answer: (C)

Phosphodiesterase plays a crucial role in regulating the levels of cyclic adenosine monophosphate (cAMP) within cells. Specifically, its function is to hydrolyze cAMP, breaking it down into AMP. This degradation process is significant for modulating the signal pathway mediated by cAMP, which is involved in transmitting various hormonal and physiological signals within the cell.

When cAMP levels are high, it can activate protein kinase A (PKA), which then phosphorylates various target proteins, leading to diverse cellular responses. By breaking down cAMP, phosphodiesterase effectively terminates or dampens the signaling pathway, ensuring that the cellular response is appropriately regulated and preventing prolonged or excessive signaling. Thus, the role of phosphodiesterase in this context is to maintain homeostasis by carefully controlling the concentration of cAMP and, consequently, the intensity and duration of its signaling effects.