In relation to gene expression, what role does cAMP primarily serve?

cAMP, or cyclic adenosine monophosphate, primarily functions as a second messenger in various signaling pathways, particularly those involving G-protein coupled receptors. When a signal molecule binds to a receptor, it can activate an enzyme called adenylate cyclase, which converts ATP into cAMP. The increase in cAMP levels within the cell triggers a cascade of events, activating protein kinase A (PKA) and leading to various cellular responses, including the activation of certain transcription factors.

This activation of signaling pathways impacts gene expression, as PKA can phosphorylate transcription factors that either enhance or inhibit the transcription of specific genes. Therefore, the role of cAMP is critical in regulating gene expression by acting as a mediator of signal transduction that ultimately leads to the activation of downstream actions, such as changes in gene transcription relevant for processes like metabolism, cell growth, and differentiation.

While the other options refer to different aspects of gene regulation or cellular processes, they do not directly capture the specific function of cAMP in gene expression.