Cyclic adenosine monophosphate

Identifiers

CAS Number

60-92-4^Y

CHEBI:17489^Y

5851^Y

DB02527^Y

Jmol 3D model

C00575^Y

E0399OZS9N^Y

InChI=1S/C10H12N5O6P/c11-8-5-9(13-2-12-8)15(3-14-5)10-6(16)7-4(20-10)1-19-22(17,18)21-7/h2-4,6-7,10,16H,1H2,(H,17,18)(H2,11,12,13)/t4-,6-,7-,10-/m1/s1^Y
Key: IVOMOUWHDPKRLL-KQYNXXCUSA-N^Y
InChI=1/C10H12N5O6P/c11-8-5-9(13-2-12-8)15(3-14-5)10-6(16)7-4(20-10)1-19-22(17,18)21-7/h2-4,6-7,10,16H,1H2,(H,17,18)(H2,11,12,13)/t4-,6-,7-,10-/m1/s1
Key: IVOMOUWHDPKRLL-KQYNXXCUBU

SMILES

c1nc(c2c(n1)n(cn2)[C@H]3[C@@H]([C@H]4[C@H](O3)COP(=O)(O4)O)O)N

Properties

Chemical formula

C₁₀H₁₂N₅O₆P

Molar mass

329.206 g/mol

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

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Infobox references

Cyclic adenosine monophosphate (cAMP, cyclic AMP, or 3',5'-cyclic adenosine monophosphate) is a second messenger important in many biological processes. cAMP is a derivative of adenosine triphosphate (ATP) and used for intracellular signal transduction in many different organisms, conveying the cAMP-dependent pathway.

History

Earl Sutherland of Case Western Reserve University won a Nobel Prize in Physiology or Medicine in 1971 "for his discoveries concerning the mechanisms of the action of hormones," especially epinephrine, via second messengers (such as cyclic adenosine monophosphate, cyclic AMP).

Synthesis and decomposition

Cyclic AMP is synthesized from ATP by adenylate cyclase located on the inner side of the plasma membrane and anchored at various locations in the interior of the cell.^[1] Adenylate cyclase is activated by a range of signaling molecules through the activation of adenylate cyclase stimulatory G (G_s)-protein-coupled receptors. Adenylate cyclase is inhibited by agonists of adenylate cyclase inhibitory G (G_i)-protein-coupled receptors. Liver adenylate cyclase responds more strongly to glucagon, and muscle adenylate cyclase responds more strongly to adrenaline.

cAMP decomposition into AMP is catalyzed by the enzyme phosphodiesterase.

Functions

cAMP is a second messenger, used for intracellular signal transduction, such as transferring into cells the effects of hormones like glucagon and adrenaline, which cannot pass through the plasma membrane. It is involved in the activation of protein kinases and regulates the effects of adrenaline and glucagon. cAMP also binds to and regulates the function of ion channels such as the HCN channels and a few other cyclic nucleotide-binding proteins such as Epac1 and RAPGEF2.

Role of cAMP in eukaryotic cells

Main article: function of cAMP-dependent protein kinase

cAMP and its associated kinases function in several biochemical processes, including the regulation of glycogen, sugar, and lipid metabolism.

In eukaryotes, cyclic AMP works by activating protein kinase A (PKA, or cAMP-dependent protein kinase). PKA is normally inactive as a tetrameric holoenzyme, consisting of two catalytic and two regulatory units (C₂R₂), with the regulatory units blocking the catalytic centers of the catalytic units.

Cyclic AMP binds to specific locations on the regulatory units of the protein kinase, and causes dissociation between the regulatory and catalytic subunits, thus enabling those catalytic units to phosphorylate substrate proteins.

The active subunits catalyze the transfer of phosphate from ATP to specific serine or threonine residues of protein substrates. The phosphorylated proteins may act directly on the cell's ion channels, or may become activated or inhibited enzymes. Protein kinase A can also phosphorylate specific proteins that bind to promoter regions of DNA, causing increased expression of specific genes. Not all protein kinases respond to cAMP. Several classes of protein kinases, including protein kinase C, are not cAMP-dependent.

Further effects mainly depend on cAMP-dependent protein kinase, which vary based on the type of cell.

Still, there are some minor PKA-independent functions of cAMP, e.g., activation of calcium channels, providing a minor pathway by which growth hormone-releasing hormone causes a release of growth hormone.^[2]

However, the view that the majority of the effects of cAMP are controlled by PKA is an outdated one. In 1998 a family of cAMP-sensitive proteins with guanine nucleotide exchange factor (GEF) activity was discovered. These are termed Exchange proteins activated by cAMP (Epac) and the family comprises Epac1 and Epac2. The mechanism of activation is similar to that of PKA: the GEF domain is usually masked by the N-terminal region containing the cAMP binding domain. When cAMP binds, the domain dissociates and exposes the now-active GEF domain, allowing Epac to activate small Ras-like GTPase proteins, such as Rap1.

Additional role of secreted cAMP in social amoebas

Role of cAMP in bacteria

In bacteria, the level of cAMP varies depending on the medium used for growth. In particular, cAMP is low when glucose is the carbon source. This occurs through inhibition of the cAMP-producing enzyme, adenylate cyclase, as a side-effect of glucose transport into the cell. The transcription factor cAMP receptor protein (CRP) also called CAP (catabolite gene activator protein) forms a complex with cAMP and thereby is activated to bind to DNA. CRP-cAMP increases expression of a large number of genes, including some encoding enzymes that can supply energy independent of glucose.

cAMP, for example, is involved in the positive regulation of the lac operon. In an environment with a low glucose concentration, cAMP accumulates and binds to the allosteric site on CRP (cAMP receptor protein), a transcription activator protein. The protein assumes its active shape and binds to a specific site upstream of the lac promoter, making it easier for RNA polymerase to bind to the adjacent promoter to start transcription of the lac operon, increasing the rate of lac operon transcription. With a high glucose concentration, the cAMP concentration decreases, and the CRP disengages from the lac operon.

Pathology

Role of cAMP in human carcinoma

Some research has suggested that a deregulation of cAMP pathways and an aberrant activation of cAMP-controlled genes is linked to the growth of some cancers.^[3]^[4]^[5]

Role of cAMP in prefrontal cortex disorders

Recent research suggests that cAMP affects the function of higher-order thinking in the prefrontal cortex through its regulation of ion channels called hyperpolarization-activated cyclic nucleotide-gated channels (HCN). When cAMP stimulates the HCN, the channels open, closing the brain cell to communication and thus interfering with the function of the prefrontal cortex. This research, especially the cognitive deficits in age-related illnesses and ADHD, is of interest to researchers studying the brain.^[6]

References

↑ Rahman N, Buck J, Levin LR. pH sensing via bicarbonate-regulated "soluble" adenylate cyclase (sAC) Front Physiol. 2013 Nov 25;4:343. eCollection 2013. Review. PMID 4324443
↑ GeneGlobe -> GHRH Signaling Retrieved on May 31, 2009
↑ American Association for Cancer Research (cAMP-responsive Genes and Tumor Progression)
↑ American Association for Cancer Research (cAMP Dysregulation and Melonoma)
↑ American Association for Cancer Research (cAMP-binding Proteins' Presence in Tumors)
↑ ScienceDaily ::Brain Networks Strengthened By Closing Ion Channels, Research Could Lead To ADHD Treatment

Additional images

cAMP represented in three ways
Adenosine triphosphate

Intracellular signaling peptides and proteins

MAP

see MAP kinase pathway

Calcium

G protein

Heterotrimeric

cAMP:	Heterotrimeric G protein Gs/Gi Adenylate cyclase cAMP 3',5'-cyclic-AMP phosphodiesterase Protein kinase A

cGMP:	Transducin Guanylate cyclase cGMP 3',5'-cyclic-GMP phosphodiesterase Protein kinase G

G alpha subunit G_α GNAO1 GNAI1 GNAI2 GNAI3 GNAT1 GNAT2 GNAT3 GNAZ GNAS GNAL GNAQ GNA11 GNA12 GNA13 GNA14 GNA15/GNA16

G beta-gamma complex G_β GNB1 GNB2 GNB3 GNB4 GNB5 G_γ GNGT1 GNGT2 GNG2 GNG3 GNG4 GNG5 GNG7 GNG8 GNG10 GNG11 GNG12 GNG13 BSCL2

G protein-coupled receptor kinase AMP-activated protein kinase

Monomeric

Cyclin

Lipid

Other protein kinase

Serine/threonine:	Casein kinase 1 2 eIF-2 kinase EIF2AK3 Glycogen synthase kinase GSK1 GSK2 GSK-3 GSK3A GSK3B IκB kinase CHUK IKK2 IKBKG Interleukin-1 receptor-associated kinase IRAK1 IRAK2 IRAK3 IRAK4 Lim kinase LIMK1 LIMK2 p21-activated kinases PAK1 PAK2 PAK3 PAK4 Rho-associated protein kinase ROCK1 ROCK2 Ribosomal s6 kinase RPS6KA1

Tyrosine:	ZAP70 Focal adhesion protein-tyrosine kinase PTK2 PTK2B BTK

both	Dual-specificity kinase

Other protein phosphatase

Serine/threonine:	Protein phosphatase 2

Tyrosine:	protein tyrosine phosphatase: Receptor-like protein tyrosine phosphatase Sh2 domain-containing protein tyrosine phosphatase

both:	Dual-specificity phosphatase

Apoptosis

see apoptosis signaling pathway

GTP-binding protein regulators

see GTP-binding protein regulators

Other

see also deficiencies of intracellular signaling peptides and proteins

Nucleic acid constituents

Nucleobase

Nucleoside

Ribonucleoside	Adenosine Guanosine 5-Methyluridine Uridine 5-Methylcytidine Cytidine Inosine Xanthosine Wybutosine

Deoxyribonucleoside	Deoxyadenosine Deoxyguanosine Thymidine Deoxyuridine Deoxycytidine Deoxyinosine Deoxyxanthosine

Nucleotide
(Nucleoside monophosphate)

Ribonucleotide	AMP GMP m⁵UMP UMP CMP IMP XMP

Deoxyribonucleotide	dAMP dGMP dTMP dUMP dCMP dIMP dXMP

Cyclic nucleotide	cAMP cGMP c-di-GMP cADPR

Nucleoside diphosphate

ADP GDP m⁵UDP UDP CDP

dADP dGDP dTDP dUDP dCDP

Nucleoside triphosphate

ATP GTP m⁵UTP UTP CTP ITP XTP

dATP dGTP dTTP dUTP dCTP dITP dXTP

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