Signaling by cAMP

The targets of cAMP include:

1. cAMP-dependent protein kinase (PKA).
2. Cyclic nucleotide gated ion channels.
3. Guanine exchanging factors Epac1 and Epac2 that regulate the activity of Rap1.

PKA is its principal target. 

Figure 6-F-1.  A cAMP/PKA signaling pathway.  PKA consists of two catalytic subunits and two regulatory subunits.  cAMP binds to two sites on each regulatory subunit.  Binding of four cAMP molecules causes the release of free and active catalytic subunits, which may phosphorylate serine and threonine residues on target proteins.  In this figure, the active subunit phosphorylates a CREB protein, resulting in transcription.

The cAMP pathway may "cross talk" with other signaling pathways.  See the following review articles.

Review Articles:

Regulation and organization of adenylyl cyclases and cAMP - Biochem. J., 2003.

Cyclic AMP-specific PDE4 Phosphodiesterases as Critical Components of Cyclic AMP Signaling - J. Bio. Chem., 2003.

Cell-Type Specific Integration of Cross-Talk between Extracellular Signal-Regulated Kinase and cAMP Signaling - Molecular Pharmacology, 2000.