How does cyclic AMP help transmit hormone signals inside a cell?

Cyclic AMP (cAMP) functions as a second messenger, a molecule that transmits signals from hormones (the "first messengers") to intracellular targets. Because cAMP is small, it diffuses rapidly through the cytoplasm, allowing for the quick propagation of biological information throughout the cell.1

The process typically follows these steps:
* Synthesis: When a hormone, such as epinephrine, binds to a cell membrane receptor, it activates G-proteins. These proteins stimulate the enzyme adenylyl cyclase to synthesize cAMP.12
* Signal Propagation: Once produced, cAMP acts as a regulatory molecule. It often activates other enzymes—such as those involved in carbohydrate metabolism—through allosteric control, where it binds to a site other than the enzyme's active site to modify its catalytic activity.12
* Regulation: The cell maintains control over this signaling pathway by regulating the synthesis and degradation of cAMP. For instance, the enzyme phosphodiesterase degrades cAMP, a process that can be inhibited by substances like caffeine to enhance the signal.1