cyclasecAMP

CyclasecAMP refers to the family of enzymes that catalyze the formation of cyclic adenosine monophosphate (cAMP) from ATP. The most studied members are adenylyl cyclases (ACs), including membrane-bound isoforms in many organisms and soluble adenylyl cyclases (sAC) located in the cytosol and organelles. These enzymes convert ATP into 3',5'-cyclic AMP, producing a key second messenger in cellular signaling.

In animal cells, AC activity is tightly regulated by heterotrimeric G proteins: Gs stimulates most AC isoforms, increasing cAMP in response to extracellular signals such as hormones and neurotransmitters, while Gi inhibits their activity. Additional regulatory inputs include Ca2+/calmodulin, other protein kinases, and direct pharmacological activators such as forskolin. Soluble ACs respond to metabolic cues such as bicarbonate and calcium, enabling cAMP production in intracellular compartments.

cAMP serves as a versatile second messenger, translating extracellular cues into cellular responses. It activates effector proteins such as protein kinase A (PKA), Epac (exchange proteins directly activated by cAMP), and cyclic nucleotide-gated ion channels. Through these effectors, cAMP modulates phosphorylation events, gene expression via CREB, metabolism, ion transport, and neuronal signaling. The spatial distribution of cAMP pools—membrane-associated versus cytosolic or organellar—affects the specificity of signaling outcomes.

Biological and clinical relevance stems from the ubiquity of cAMP signaling. Dysregulation of cyclasecAMP activity is linked to metabolic and cardiovascular disorders, learning and memory processes, and various disease states. Some pathogens also manipulate host cAMP signaling by deploying bacterial adenylyl cyclases to alter host physiology.