Biochemistry · Molecule
Cyclic AMP (cAMP) !
The classic second messenger: adenylyl cyclase makes it from ATP when a hormone arrives, and phosphodiesterase destroys it.
Updated 2026-11-01
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Key facts
- Adenylyl cyclase makes it (ATP → cAMP + pyrophosphate) and phosphodiesterases break it down (cAMP → AMP).
- It activates PKA, the Epac protein and some ion channels (vision and smell, for example, use cyclic nucleotides).
- Second messenger of glucagon, adrenaline (β), ACTH, TSH, LH, FSH, PTH, ADH (V2), hCG, CRH, GHRH and calcitonin.
- Insulin lowers it by activating phosphodiesterase 3B: that is how it stops lipolysis and glycogen breakdown.
- Also called
- Adenosine 3',5'-cyclic monophosphate, cAMP
- Formula
- C10H12N5O6P
- PubChem
- CID 6076
Structure
- Adenine linked to ribose, with a single phosphate forming a ring between the ribose 3' and 5' carbons.
- That cyclic phosphodiester bond is what phosphodiesterase breaks to give 5'-AMP.
Clinical notes
- Caffeine and theophylline inhibit phosphodiesterases and prolong cAMP (bronchodilation, cardiac stimulation).
- Phosphodiesterase 3 inhibitors (milrinone) are used in acute heart failure; phosphodiesterase 4 inhibitors in inflammatory skin and lung disease.
- Cholera diarrhoea is due to high cAMP in the enterocyte.
Related conditions
Related
- Adenylyl cyclase
- Protein kinase A (PKA)
- G protein-coupled receptors and cAMP
- Glucagon signalling
- ATP (adenosine triphosphate)
- Insulin signalling
Test yourself
Think of the answer, then tap the question to see it.
Which enzyme makes cAMP and which breaks it down?
Adenylyl cyclase makes it from ATP and phosphodiesterase breaks it down to 5'-AMP.
How does insulin lower adipocyte cAMP?
Through Akt it activates phosphodiesterase 3B, which breaks down cAMP and switches off hormone-sensitive lipase.
Why does theophylline raise cAMP?
Because it inhibits the phosphodiesterases that break it down.
Molecules are shown in their neutral form, as the databases deposit them; in the cell the acids and phosphates are ionised.
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Camp (CID 6076) (PubChem, NCBI, 2026) · Public domain; PRKACA: cAMP-dependent protein kinase catalytic subunit alpha (human) (UniProt, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).
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