Metabolism of nitric oxide (Homo sapiens)

From WikiPathways

Jump to: navigation, search
234, 9, 13, 37, 4610, 2451223412, 18, 27, 4433, 35, 382819, 39169, 13, 25, 482816, 40229262611, 21, 36, 453, 32, 501, 47522, 4116, 26, 30742Golgi lumenendocytic vesicle membranecytosollipid dropletheme CALM1:4xCa2+Zn2+ FAD WASL 2xPalmC-MyrG-NOS3 2xPalmC-MyrG-NOS3 p-T308,S473-AKT1 Zn2+ FAD CAV1 heme FAD DNM2Zn2+ H2O2xPalmC-MyrG-p-S1177-NOS3 HSP90AA1 FAD eNOS:Caveolin-1:NOSTRIN complexFMN Zn2+ Zn2+ NOSTRIN p-S1177-eNOS:CaM:HSP90:p-AKT1:BH2BH4 CALM1 NOSTRIN heme Tetrahydrobiopterin(BH4) synthesis,recycling, salvageand regulationBH2FAD CAV1 2xPalmC-MyrG-NOS3 eNOS:Caveolin-1:NOSTRIN:dynamin-2:N-WASPCALM1 DMANOSIP FMN Zn2+ NO3-NOSTRIN eNOS:NOSIPheme CYGB dimer:O2FAD eNOS:Caveolin-1:CaMNODNM2 FMN APT1 homodimerFAD CYGB myristoylated eNOSdimereNOS:NOSIPFMN CALM1 heme heme FMN 2xPalmC-MyrG-NOS3 Ca2+ NADP+p-T308,S473-AKT1 Ca2+ FMN ATPFMN FAD FMN Zn2+ 2xPalmC-MyrG-NOS3 WASL CAV1 NADP+2xPalmC-MyrG-NOS3 NOSTRIN homotrimerZn2+ 2xPalmC-MyrG-p-S1177-NOS3 heme eNOS:CaM:HSP90:p-AKT1CYGB dimerN-WASPheme O2Ca2+ p-T308,S473-AKT1 Zn2+ FMN BH4 HSP90AA1 Zn2+ Ca2+ FAD CALM1 BH4 NOSIPZDHHC21eNOS:Caveolin-1:NOSTRIN:Dynamin-2FMN FAD heme FMN H+Zn2+ DNM2 p-SPR dimerPALMNOS3MyrG-NOS3 PALM-CoACAV1FMN 2xPalmC-MyrG-NOS3 heme ADPCALM1 CAV1 MYS-CoAeNOS:CaM:HSP90FAD NOSTRIN 2xPalmC-MyrG-NOS3 heme p-S213-SPR NADPHeNOS:Caveolin-1palmitoylated,myristoylated eNOSdimerZn2+ LYPLA1 HSP90AA1heme FMN Ca2+ 2xPalmC-MyrG-NOS3NADPHL-Citp-S1177-eNOS:CaM:HSP90:p-AKT1FMN CALM1 2xPalmC-MyrG-NOS3 FAD Peroxynitriteheme NADPHFAD ADMAZn2+ FMN sepiapterineNOS:Caveolin-1:NOSTRIN:dynamin-2:N-WASPp-T308,S473-AKT1NOSTRIN HSP90AA1 HSP90AA1 myristoylated eNOSdimerFMN MyrG-NOS3 heme p-T308,S473-AKT1 FAD DDAH1,2Ca2+ NOSIP PIP3 activates AKTsignalingCYGB NADP+DNM2 Ca2+ Zn2+ Ca2+ L-ArgCAV1 H+O2.-FAD p-S1177-eNOS:CaM:HSP90:p-AKT1:BH4eNOS:Caveolin-1:CaM:HSP90FMN CALM1 heme CAV1 heme BH4 DDAH2 O2 NADP+BH4 HSP90AA1 Zn2+ HSP90AA1 MyrG-NOS3BH4 O2BH4BH2 2xPalmC-MyrG-p-S1177-NOS3 Zn2+ FAD BH4 Zn2+ CALM1 heme 2xPalmC-MyrG-NOS3 CAV1 DDAH1 NADPHheme 2xPalmC-MyrG-NOS3 FAD heme 2xPalmC-MyrG-NOS3 6, 15, 17, 314914308, 20, 4349


Nitric oxide (NO), a multifunctional second messenger, is implicated in physiological functions in mammals that range from immune response and potentiation of synaptic transmission to dilation of blood vessels and muscle relaxation. NO is a highly active molecule that diffuses across cell membranes and cannot be stored inside the producing cell. Its signaling capacity must be controlled at the levels of biosynthesis and local availability. Indeed, NO production by NO synthases is under complex and tight control, being regulated at transcriptional and translational levels, through co- and posttranslational modifications, and by subcellular localization. NO is synthesized from L-arginine by a family of nitric oxide synthases (NOS). Three NOS isoforms have been characterized: neuronal NOS (nNOS, NOS1) primarily found in neuronal tissue and skeletal muscle; inducible NOS (iNOS, NOS2) originally isolated from macrophages and later discovered in many other cells types; and endothelial NOS (eNOS, NOS3) present in vascular endothelial cells, cardiac myocytes, and in blood platelets. The enzymatic activity of all three isoforms is dependent on calmodulin, which binds to nNOS and eNOS at elevated intracellular calcium levels, while it is tightly associated with iNOS even at basal calcium levels. As a result, the enzymatic activity of nNOS and eNOS is modulated by changes in intracellular calcium levels, leading to transient NO production, while iNOS continuously releases NO independent of fluctuations in intracellular calcium levels and is mainly regulated at the gene expression level (Pacher et al. 2007).

The NOS enzymes share a common basic structural organization and requirement for substrate cofactors for enzymatic activity. A central calmodulin-binding motif separates an oxygenase (NH2-terminal) domain from a reductase (COOH-terminal) domain. Binding sites for cofactors NADPH, FAD, and FMN are located within the reductase domain, while binding sites for tetrahydrobiopterin (BH4) and heme are located within the oxygenase domain. Once calmodulin binds, it facilitates electron transfer from the cofactors in the reductase domain to heme enabling nitric oxide production. Both nNOS and eNOS contain an additional insert (40-50 amino acids) in the middle of the FMN-binding subdomain that serves as autoinhibitory loop, destabilizing calmodulin binding at low calcium levels and inhibiting electron transfer from FMN to the heme in the absence of calmodulin. iNOS does not contain this insert.<p>Because NOS enzymatic activity is modulated by the presence of its substrates and cofactors within the cell, under certain conditions, NOS may generate superoxide instead of NO, a process referred to as uncoupling (uncoupling of NADPH oxidation and NO synthesis).<p>The molecular details of eNOS function are annotated here. View original pathway at:Reactome.</div>


Pathway is converted from Reactome ID: 202131
Reactome version: 66
Reactome Author 
Reactome Author: Hemish, J

Quality Tags

Ontology Terms



View all...
  1. Takahashi S, Mendelsohn ME.; ''Synergistic activation of endothelial nitric-oxide synthase (eNOS) by HSP90 and Akt: calcium-independent eNOS activation involves formation of an HSP90-Akt-CaM-bound eNOS complex.''; PubMed Europe PMC
  2. Liu J, Sessa WC.; ''Identification of covalently bound amino-terminal myristic acid in endothelial nitric oxide synthase.''; PubMed Europe PMC
  3. Wang Y, Monzingo AF, Hu S, Schaller TH, Robertus JD, Fast W.; ''Developing dual and specific inhibitors of dimethylarginine dimethylaminohydrolase-1 and nitric oxide synthase: toward a targeted polypharmacology to control nitric oxide.''; PubMed Europe PMC
  4. Smagghe BJ, Trent JT, Hargrove MS.; ''NO dioxygenase activity in hemoglobins is ubiquitous in vitro, but limited by reduction in vivo.''; PubMed Europe PMC
  5. Sawabe K, Yamamoto K, Harada Y, Ohashi A, Sugawara Y, Matsuoka H, Hasegawa H.; ''Cellular uptake of sepiapterin and push-pull accumulation of tetrahydrobiopterin.''; PubMed Europe PMC
  6. Crabtree MJ, Channon KM.; ''Synthesis and recycling of tetrahydrobiopterin in endothelial function and vascular disease.''; PubMed Europe PMC
  7. Gratton JP, Fontana J, O'Connor DS, Garcia-Cardena G, McCabe TJ, Sessa WC.; ''Reconstitution of an endothelial nitric-oxide synthase (eNOS), hsp90, and caveolin-1 complex in vitro. Evidence that hsp90 facilitates calmodulin stimulated displacement of eNOS from caveolin-1.''; PubMed Europe PMC
  8. Syed NA, Horner KN, Misra V, Khandelwal RL.; ''Different cellular localization, translocation, and insulin-induced phosphorylation of PKBalpha in HepG2 cells and hepatocytes.''; PubMed Europe PMC
  9. Trent JT, Hargrove MS.; ''A ubiquitously expressed human hexacoordinate hemoglobin.''; PubMed Europe PMC
  10. Fernández-Hernando C, Fukata M, Bernatchez PN, Fukata Y, Lin MI, Bredt DS, Sessa WC.; ''Identification of Golgi-localized acyl transferases that palmitoylate and regulate endothelial nitric oxide synthase.''; PubMed Europe PMC
  11. Klatt P, Schmidt K, Werner ER, Mayer B.; ''Determination of nitric oxide synthase cofactors: heme, FAD, FMN, and tetrahydrobiopterin.''; PubMed Europe PMC
  12. Feron O, Belhassen L, Kobzik L, Smith TW, Kelly RA, Michel T.; ''Endothelial nitric oxide synthase targeting to caveolae. Specific interactions with caveolin isoforms in cardiac myocytes and endothelial cells.''; PubMed Europe PMC
  13. Hamdane D, Kiger L, Dewilde S, Green BN, Pesce A, Uzan J, Burmester T, Hankeln T, Bolognesi M, Moens L, Marden MC.; ''The redox state of the cell regulates the ligand binding affinity of human neuroglobin and cytoglobin.''; PubMed Europe PMC
  14. Chen TY, Illing M, Molday LL, Hsu YT, Yau KW, Molday RS.; ''Subunit 2 (or beta) of retinal rod cGMP-gated cation channel is a component of the 240-kDa channel-associated protein and mediates Ca(2+)-calmodulin modulation.''; PubMed Europe PMC
  15. Schmidt TS, Alp NJ.; ''Mechanisms for the role of tetrahydrobiopterin in endothelial function and vascular disease.''; PubMed Europe PMC
  16. Oess S, Icking A, Fulton D, Govers R, Müller-Esterl W.; ''Subcellular targeting and trafficking of nitric oxide synthases.''; PubMed Europe PMC
  17. Thöny B, Auerbach G, Blau N.; ''Tetrahydrobiopterin biosynthesis, regeneration and functions.''; PubMed Europe PMC
  18. García-Cardeña G, Martasek P, Masters BS, Skidd PM, Couet J, Li S, Lisanti MP, Sessa WC.; ''Dissecting the interaction between nitric oxide synthase (NOS) and caveolin. Functional significance of the nos caveolin binding domain in vivo.''; PubMed Europe PMC
  19. Jourd'heuil D, Jourd'heuil FL, Kutchukian PS, Musah RA, Wink DA, Grisham MB.; ''Reaction of superoxide and nitric oxide with peroxynitrite. Implications for peroxynitrite-mediated oxidation reactions in vivo.''; PubMed Europe PMC
  20. Andjelković M, Maira SM, Cron P, Parker PJ, Hemmings BA.; ''Domain swapping used to investigate the mechanism of protein kinase B regulation by 3-phosphoinositide-dependent protein kinase 1 and Ser473 kinase.''; PubMed Europe PMC
  21. List BM, Klösch B, Völker C, Gorren AC, Sessa WC, Werner ER, Kukovetz WR, Schmidt K, Mayer B.; ''Characterization of bovine endothelial nitric oxide synthase as a homodimer with down-regulated uncoupled NADPH oxidase activity: tetrahydrobiopterin binding kinetics and role of haem in dimerization.''; PubMed Europe PMC
  22. Dedio J, König P, Wohlfart P, Schroeder C, Kummer W, Müller-Esterl W.; ''NOSIP, a novel modulator of endothelial nitric oxide synthase activity.''; PubMed Europe PMC
  23. Pacher P, Beckman JS, Liaudet L.; ''Nitric oxide and peroxynitrite in health and disease.''; PubMed Europe PMC
  24. García-Cardeña G, Oh P, Liu J, Schnitzer JE, Sessa WC.; ''Targeting of nitric oxide synthase to endothelial cell caveolae via palmitoylation: implications for nitric oxide signaling.''; PubMed Europe PMC
  25. Fago A, Hundahl C, Dewilde S, Gilany K, Moens L, Weber RE.; ''Allosteric regulation and temperature dependence of oxygen binding in human neuroglobin and cytoglobin. Molecular mechanisms and physiological significance.''; PubMed Europe PMC
  26. Schilling K, Opitz N, Wiesenthal A, Oess S, Tikkanen R, Müller-Esterl W, Icking A.; ''Translocation of endothelial nitric-oxide synthase involves a ternary complex with caveolin-1 and NOSTRIN.''; PubMed Europe PMC
  27. Drab M, Verkade P, Elger M, Kasper M, Lohn M, Lauterbach B, Menne J, Lindschau C, Mende F, Luft FC, Schedl A, Haller H, Kurzchalia TV.; ''Loss of caveolae, vascular dysfunction, and pulmonary defects in caveolin-1 gene-disrupted mice.''; PubMed Europe PMC
  28. Vásquez-Vivar J, Martásek P, Whitsett J, Joseph J, Kalyanaraman B.; ''The ratio between tetrahydrobiopterin and oxidized tetrahydrobiopterin analogues controls superoxide release from endothelial nitric oxide synthase: an EPR spin trapping study.''; PubMed Europe PMC
  29. García-Cardeña G, Fan R, Shah V, Sorrentino R, Cirino G, Papapetropoulos A, Sessa WC.; ''Dynamic activation of endothelial nitric oxide synthase by Hsp90.''; PubMed Europe PMC
  30. Icking A, Matt S, Opitz N, Wiesenthal A, Müller-Esterl W, Schilling K.; ''NOSTRIN functions as a homotrimeric adaptor protein facilitating internalization of eNOS.''; PubMed Europe PMC
  31. Schulz E, Jansen T, Wenzel P, Daiber A, Münzel T.; ''Nitric oxide, tetrahydrobiopterin, oxidative stress, and endothelial dysfunction in hypertension.''; PubMed Europe PMC
  32. Cillero-Pastor B, Mateos J, Fernández-López C, Oreiro N, Ruiz-Romero C, Blanco FJ.; ''Dimethylarginine dimethylaminohydrolase 2, a newly identified mitochondrial protein modulating nitric oxide synthesis in normal human chondrocytes.''; PubMed Europe PMC
  33. Michell BJ, Griffiths JE, Mitchelhill KI, Rodriguez-Crespo I, Tiganis T, Bozinovski S, de Montellano PR, Kemp BE, Pearson RB.; ''The Akt kinase signals directly to endothelial nitric oxide synthase.''; PubMed Europe PMC
  34. Michel JB, Feron O, Sacks D, Michel T.; ''Reciprocal regulation of endothelial nitric-oxide synthase by Ca2+-calmodulin and caveolin.''; PubMed Europe PMC
  35. Dimmeler S, Fleming I, Fisslthaler B, Hermann C, Busse R, Zeiher AM.; ''Activation of nitric oxide synthase in endothelial cells by Akt-dependent phosphorylation.''; PubMed Europe PMC
  36. Bredt DS, Snyder SH.; ''Nitric oxide: a physiologic messenger molecule.''; PubMed Europe PMC
  37. Halligan KE, Jourd'heuil FL, Jourd'heuil D.; ''Cytoglobin is expressed in the vasculature and regulates cell respiration and proliferation via nitric oxide dioxygenation.''; PubMed Europe PMC
  38. Fulton D, Gratton JP, McCabe TJ, Fontana J, Fujio Y, Walsh K, Franke TF, Papapetropoulos A, Sessa WC.; ''Regulation of endothelium-derived nitric oxide production by the protein kinase Akt.''; PubMed Europe PMC
  39. Reiter CD, Teng RJ, Beckman JS.; ''Superoxide reacts with nitric oxide to nitrate tyrosine at physiological pH via peroxynitrite.''; PubMed Europe PMC
  40. Govers R, Rabelink TJ.; ''Cellular regulation of endothelial nitric oxide synthase.''; PubMed Europe PMC
  41. Zimmermann K, Opitz N, Dedio J, Renne C, Muller-Esterl W, Oess S.; ''NOSTRIN: a protein modulating nitric oxide release and subcellular distribution of endothelial nitric oxide synthase.''; PubMed Europe PMC
  42. Michel T.; ''Targeting and translocation of endothelial nitric oxide synthase.''; PubMed Europe PMC
  43. Andjelković M, Alessi DR, Meier R, Fernandez A, Lamb NJ, Frech M, Cron P, Cohen P, Lucocq JM, Hemmings BA.; ''Role of translocation in the activation and function of protein kinase B.''; PubMed Europe PMC
  44. Ghosh S, Gachhui R, Crooks C, Wu C, Lisanti MP, Stuehr DJ.; ''Interaction between caveolin-1 and the reductase domain of endothelial nitric-oxide synthase. Consequences for catalysis.''; PubMed Europe PMC
  45. Tuteja N, Chandra M, Tuteja R, Misra MK.; ''Nitric Oxide as a Unique Bioactive Signaling Messenger in Physiology and Pathophysiology.''; PubMed Europe PMC
  46. Gardner PR.; ''Nitric oxide dioxygenase function and mechanism of flavohemoglobin, hemoglobin, myoglobin and their associated reductases.''; PubMed Europe PMC
  47. Fontana J, Fulton D, Chen Y, Fairchild TA, McCabe TJ, Fujita N, Tsuruo T, Sessa WC.; ''Domain mapping studies reveal that the M domain of hsp90 serves as a molecular scaffold to regulate Akt-dependent phosphorylation of endothelial nitric oxide synthase and NO release.''; PubMed Europe PMC
  48. Burmester T, Ebner B, Weich B, Hankeln T.; ''Cytoglobin: a novel globin type ubiquitously expressed in vertebrate tissues.''; PubMed Europe PMC
  49. Venema RC, Ju H, Zou R, Ryan JW, Venema VJ.; ''Subunit interactions of endothelial nitric-oxide synthase. Comparisons to the neuronal and inducible nitric-oxide synthase isoforms.''; PubMed Europe PMC
  50. Forbes SP, Druhan LJ, Guzman JE, Parinandi N, Zhang L, Green-Church KB, Cardounel AJ.; ''Mechanism of 4-HNE mediated inhibition of hDDAH-1: implications in no regulation.''; PubMed Europe PMC
  51. Berka V, Yeh HC, Gao D, Kiran F, Tsai AL.; ''Redox function of tetrahydrobiopterin and effect of L-arginine on oxygen binding in endothelial nitric oxide synthase.''; PubMed Europe PMC


View all...
101210view11:10, 1 November 2018ReactomeTeamreactome version 66
100748view20:35, 31 October 2018ReactomeTeamreactome version 65
100292view19:12, 31 October 2018ReactomeTeamreactome version 64
99838view15:56, 31 October 2018ReactomeTeamreactome version 63
99395view14:33, 31 October 2018ReactomeTeamreactome version 62 (2nd attempt)
99089view12:39, 31 October 2018ReactomeTeamreactome version 62
93867view13:41, 16 August 2017ReactomeTeamreactome version 61
93432view11:23, 9 August 2017ReactomeTeamreactome version 61
86524view09:20, 11 July 2016ReactomeTeamreactome version 56
83235view10:27, 18 November 2015ReactomeTeamVersion54
81634view13:10, 21 August 2015ReactomeTeamVersion53
77097view08:39, 17 July 2014ReactomeTeamFixed remaining interactions
76803view12:18, 16 July 2014ReactomeTeamFixed remaining interactions
76126view10:19, 11 June 2014ReactomeTeamRe-fixing comment source
75838view11:40, 10 June 2014ReactomeTeamReactome 48 Update
75197view09:43, 9 May 2014AnweshaFixing comment source for displaying WikiPathways description
74846view10:07, 30 April 2014ReactomeTeamReactome46
70998view15:37, 22 September 2013EgonwImproved the layout, so that references and text are better readable in the current PV.
68887view17:27, 8 July 2013MaintBotUpdated to 2013 gpml schema
44897view10:20, 6 October 2011MartijnVanIerselOntology Term : 'classic metabolic pathway' added !
42166view23:32, 4 March 2011MaintBotModified categories
42068view21:54, 4 March 2011MaintBotAutomatic update
39876view05:54, 21 January 2011MaintBotNew pathway

External references


View all...
NameTypeDatabase referenceComment
2xPalmC-MyrG-NOS3 ProteinP29474 (Uniprot-TrEMBL)
2xPalmC-MyrG-NOS3ProteinP29474 (Uniprot-TrEMBL)
2xPalmC-MyrG-p-S1177-NOS3 ProteinP29474 (Uniprot-TrEMBL)
ADMAMetaboliteCHEBI:25682 (ChEBI)
ADPMetaboliteCHEBI:16761 (ChEBI)
APT1 homodimerComplexR-HSA-203655 (Reactome)
ATPMetaboliteCHEBI:15422 (ChEBI)
BH2 MetaboliteCHEBI:15375 (ChEBI)
BH2MetaboliteCHEBI:15375 (ChEBI)
BH4 MetaboliteCHEBI:15372 (ChEBI)
BH4MetaboliteCHEBI:15372 (ChEBI)
CALM1 ProteinP0DP23 (Uniprot-TrEMBL)
CALM1:4xCa2+ComplexR-HSA-74294 (Reactome)
CAV1 ProteinQ03135 (Uniprot-TrEMBL)
CAV1ProteinQ03135 (Uniprot-TrEMBL)
CYGB ProteinQ8WWM9 (Uniprot-TrEMBL)
CYGB dimer:O2ComplexR-HSA-5340212 (Reactome)
CYGB dimerComplexR-HSA-5340240 (Reactome)
Ca2+ MetaboliteCHEBI:29108 (ChEBI)
DDAH1 ProteinO94760 (Uniprot-TrEMBL)
DDAH1,2ComplexR-HSA-6786641 (Reactome)
DDAH2 ProteinO95865 (Uniprot-TrEMBL)
DMAMetaboliteCHEBI:17170 (ChEBI)
DNM2 ProteinP50570 (Uniprot-TrEMBL)
DNM2ProteinP50570 (Uniprot-TrEMBL)
FAD MetaboliteCHEBI:16238 (ChEBI)
FMN MetaboliteCHEBI:17621 (ChEBI)
H+MetaboliteCHEBI:15378 (ChEBI)
H2OMetaboliteCHEBI:15377 (ChEBI)
HSP90AA1 ProteinP07900 (Uniprot-TrEMBL)
HSP90AA1ProteinP07900 (Uniprot-TrEMBL)
L-ArgMetaboliteCHEBI:32682 (ChEBI)
L-CitMetaboliteCHEBI:16349 (ChEBI)
LYPLA1 ProteinO75608 (Uniprot-TrEMBL)
MYS-CoAMetaboliteCHEBI:15532 (ChEBI)
MyrG-NOS3 ProteinP29474 (Uniprot-TrEMBL)
MyrG-NOS3ProteinP29474 (Uniprot-TrEMBL)
N-WASPProteinO00401 (Uniprot-TrEMBL)
NADP+MetaboliteCHEBI:18009 (ChEBI)
NADPHMetaboliteCHEBI:16474 (ChEBI)
NO3-MetaboliteCHEBI:17632 (ChEBI)
NOMetaboliteCHEBI:16480 (ChEBI)
NOS3ProteinP29474 (Uniprot-TrEMBL)
NOSIP ProteinQ9Y314 (Uniprot-TrEMBL)
NOSIPProteinQ9Y314 (Uniprot-TrEMBL)
NOSTRIN ProteinQ8IVI9 (Uniprot-TrEMBL)
NOSTRIN homotrimerComplexR-HSA-203678 (Reactome)
O2 MetaboliteCHEBI:15379 (ChEBI)
O2.-MetaboliteCHEBI:18421 (ChEBI)
O2MetaboliteCHEBI:15379 (ChEBI)
PALM-CoAMetaboliteCHEBI:15525 (ChEBI)
PALMMetaboliteCHEBI:15756 (ChEBI)
PIP3 activates AKT signalingPathwayR-HSA-1257604 (Reactome) Signaling by AKT is one of the key outcomes of receptor tyrosine kinase (RTK) activation. AKT is activated by the cellular second messenger PIP3, a phospholipid that is generated by PI3K. In ustimulated cells, PI3K class IA enzymes reside in the cytosol as inactive heterodimers composed of p85 regulatory subunit and p110 catalytic subunit. In this complex, p85 stabilizes p110 while inhibiting its catalytic activity. Upon binding of extracellular ligands to RTKs, receptors dimerize and undergo autophosphorylation. The regulatory subunit of PI3K, p85, is recruited to phosphorylated cytosolic RTK domains either directly or indirectly, through adaptor proteins, leading to a conformational change in the PI3K IA heterodimer that relieves inhibition of the p110 catalytic subunit. Activated PI3K IA phosphorylates PIP2, converting it to PIP3; this reaction is negatively regulated by PTEN phosphatase. PIP3 recruits AKT to the plasma membrane, allowing TORC2 to phosphorylate a conserved serine residue of AKT. Phosphorylation of this serine induces a conformation change in AKT, exposing a conserved threonine residue that is then phosphorylated by PDPK1 (PDK1). Phosphorylation of both the threonine and the serine residue is required to fully activate AKT. The active AKT then dissociates from PIP3 and phosphorylates a number of cytosolic and nuclear proteins that play important roles in cell survival and metabolism. For a recent review of AKT signaling, please refer to Manning and Cantley, 2007.
PeroxynitriteMetaboliteCHEBI:25941 (ChEBI)

(BH4) synthesis, recycling, salvage

and regulation
PathwayR-HSA-1474151 (Reactome) Tetrahydrobiopterin (BH4) is an essential co-factor for the aromatic amino acid hydroxylases and glycerol ether monooxygenase and it regulates nitric oxide synthase (NOS) activity. Inherited BH4 deficiency leads to hyperphenylalaninemia, and dopamine and neurotransmitter deficiency in the brain. BH4 maintains enzymatic coupling to L-arginine oxidation to produce NO. Oxidation of BH4 to BH2 results in NOS uncoupling, resulting in superoxide (O2.-) formation rather than NO. Superoxide rapidly reacts with NO to produce peroxynitrite which can further uncouple NOS.
These reactive oxygen species (superoxide and peroxynitrite) can contribute to increased oxidative stress in the endothelium leading to atherosclerosis and hypertension (Thony et al. 2000, Crabtree and Channon 2011,Schulz et al. 2008, Schmidt and Alp 2007). The synthesis, recycling and effects of BH4 are shown here. Three enzymes are required for the de novo biosynthesis of BH4 and two enzymes for the recycling of BH4.
WASL ProteinO00401 (Uniprot-TrEMBL)
ZDHHC21ProteinQ8IVQ6 (Uniprot-TrEMBL)
Zn2+ MetaboliteCHEBI:29105 (ChEBI)
eNOS:CaM:HSP90:p-AKT1ComplexR-HSA-202113 (Reactome)
eNOS:CaM:HSP90ComplexR-HSA-202105 (Reactome)
eNOS:Caveolin-1:CaM:HSP90ComplexR-HSA-202130 (Reactome)
eNOS:Caveolin-1:CaMComplexR-HSA-202116 (Reactome)
eNOS:Caveolin-1:NOSTRIN complexComplexR-HSA-203758 (Reactome)
eNOS:Caveolin-1:NOSTRIN:Dynamin-2ComplexR-HSA-203696 (Reactome)
eNOS:Caveolin-1:NOSTRIN:dynamin-2:N-WASPComplexR-HSA-203629 (Reactome)
eNOS:Caveolin-1:NOSTRIN:dynamin-2:N-WASPComplexR-HSA-203648 (Reactome)
eNOS:Caveolin-1ComplexR-HSA-202128 (Reactome)
eNOS:NOSIPComplexR-HSA-203595 (Reactome)
eNOS:NOSIPComplexR-HSA-203623 (Reactome)
heme MetaboliteCHEBI:17627 (ChEBI)
myristoylated eNOS dimerComplexR-HSA-203619 (Reactome)
myristoylated eNOS dimerComplexR-HSA-203969 (Reactome)
p-S1177-eNOS:CaM:HSP90:p-AKT1:BH2ComplexR-HSA-1497889 (Reactome)
p-S1177-eNOS:CaM:HSP90:p-AKT1:BH4ComplexR-HSA-1497830 (Reactome)
p-S1177-eNOS:CaM:HSP90:p-AKT1ComplexR-HSA-202121 (Reactome)
p-S213-SPR ProteinP35270 (Uniprot-TrEMBL)
p-SPR dimerComplexR-HSA-1497817 (Reactome)
p-T308,S473-AKT1 ProteinP31749 (Uniprot-TrEMBL)
p-T308,S473-AKT1ProteinP31749 (Uniprot-TrEMBL)

myristoylated eNOS

ComplexR-HSA-203639 (Reactome)
sepiapterinMetaboliteCHEBI:16095 (ChEBI)

Annotated Interactions

View all...
SourceTargetTypeDatabase referenceComment
2xPalmC-MyrG-NOS3ArrowR-HSA-203567 (Reactome)
2xPalmC-MyrG-NOS3R-HSA-203700 (Reactome)
ADMAR-HSA-5693373 (Reactome)
ADMATBarR-HSA-202127 (Reactome)
ADPArrowR-HSA-202111 (Reactome)
APT1 homodimermim-catalysisR-HSA-203613 (Reactome)
ATPR-HSA-202111 (Reactome)
BH2ArrowR-HSA-1497869 (Reactome)
BH2R-HSA-1497796 (Reactome)
BH4ArrowR-HSA-1497796 (Reactome)
BH4R-HSA-1497784 (Reactome)
CALM1:4xCa2+ArrowR-HSA-202129 (Reactome)
CALM1:4xCa2+R-HSA-202110 (Reactome)
CAV1ArrowR-HSA-202144 (Reactome)
CAV1R-HSA-203712 (Reactome)
CYGB dimer:O2ArrowR-HSA-5340214 (Reactome)
CYGB dimer:O2R-HSA-5340226 (Reactome)
CYGB dimer:O2mim-catalysisR-HSA-5340226 (Reactome)
CYGB dimerArrowR-HSA-5340226 (Reactome)
CYGB dimerR-HSA-5340214 (Reactome)
DDAH1,2mim-catalysisR-HSA-5693373 (Reactome)
DMAArrowR-HSA-5693373 (Reactome)
DNM2R-HSA-203662 (Reactome)
H+R-HSA-1497869 (Reactome)
H+R-HSA-5340226 (Reactome)
H2OR-HSA-5693373 (Reactome)
HSP90AA1R-HSA-202129 (Reactome)
L-ArgR-HSA-202127 (Reactome)
L-CitArrowR-HSA-202127 (Reactome)
L-CitArrowR-HSA-5693373 (Reactome)
MYS-CoAR-HSA-203611 (Reactome)
MyrG-NOS3ArrowR-HSA-203611 (Reactome)
MyrG-NOS3R-HSA-203567 (Reactome)
N-WASPR-HSA-203565 (Reactome)
NADP+ArrowR-HSA-1497810 (Reactome)
NADP+ArrowR-HSA-1497869 (Reactome)
NADP+ArrowR-HSA-202127 (Reactome)
NADP+ArrowR-HSA-5340226 (Reactome)
NADPHR-HSA-1497810 (Reactome)
NADPHR-HSA-1497869 (Reactome)
NADPHR-HSA-202127 (Reactome)
NADPHR-HSA-5340226 (Reactome)
NO3-ArrowR-HSA-5340226 (Reactome)
NOArrowR-HSA-202127 (Reactome)
NOR-HSA-1497878 (Reactome)
NOR-HSA-5340226 (Reactome)
NOS3R-HSA-203611 (Reactome)
NOSIPR-HSA-203553 (Reactome)
NOSTRIN homotrimerR-HSA-203716 (Reactome)
O2.-ArrowR-HSA-1497810 (Reactome)
O2.-R-HSA-1497878 (Reactome)
O2R-HSA-1497810 (Reactome)
O2R-HSA-202127 (Reactome)
O2R-HSA-5340214 (Reactome)
PALM-CoAR-HSA-203567 (Reactome)
PALMArrowR-HSA-203613 (Reactome)
PeroxynitriteArrowR-HSA-1497878 (Reactome)
R-HSA-1497784 (Reactome) The cofactor tetrahydrobiopterin (BH4) ensures endothelial nitric oxide synthase (eNOS) couples electron transfer to L-arginine oxidation (Berka et al. 2004). During catalysis, electrons derived from NADPH transfer to the flavins FAD and FMN in the reductase domain of eNOS and then on to the ferric heme in the oxygenase domain of eNOS. BH4 can donate an electron to intermediates in this electron transfer and is oxidised in the process, forming the BH3 radical. This radical can be reduced back to BH4 by iron, completing the cycle and forming ferrous iron again. Heme reduction enables O2 binding and L-arginine oxidation to occur within the oxygenase domain (Stuehr et al. 2009).
R-HSA-1497796 (Reactome) The oxidation product of BH4, 7,8-dihydrobiopterin (BH2), can compete with BH4 for binding to eNOS. This can lead to the uncoupling of eNOS and can result in the formation of reactive oxygen species (Vasquez-Vivar et al. 2002).
R-HSA-1497810 (Reactome) BH2 may compete with BH4 to bind eNOS, uncoupling eNOS leading to the formation of superoxide rather than nitric oxide. BH2, the oxidised form of BH4, cannot contribute electrons to heme in the reductase domain of eNOS, thereby uncoupling it from arginine oxidation and producing superoxide from oxygen instead (Vasquez-Vivar et al. 2002).
R-HSA-1497869 (Reactome) In the first of two salvage steps to maintain BH4 levels in the cell, sepiapterin is taken up by the cell and reduced by sepiapterin reductase (SRP) to form BH2 (Sawabe et al. 2008).
R-HSA-1497878 (Reactome) Superoxide (O2.-) formed from an uncoupled eNOS action, together with nitric oxide (NO) formed from a coupled eNOS action, readily react together to fom peroxynitrite (ONOO-) (Jourd'heuil et al. 2001, Reiter et al. 2000).
R-HSA-202110 (Reactome) Caveolin inhibition of eNOS is relieved by calmodulin, which causes dissociation of eNOS from caveolin.
R-HSA-202111 (Reactome) HSP90 serves as a scaffold to promote productive interaction between AKT1 and eNOS. Due to the proximity of these proteins once complexed with HSP90, AKT1 phosphorylates eNOS at Ser1177. When Ser1177 is phosphorylated, the level of NO production is elevated two- to three-fold above basal level.

R-HSA-202127 (Reactome) Nitric oxide (NO) is produced from L-arginine by the family of nitric oxide synthases (NOS) enzymes, forming the free radical NO and citrulline as byproduct. The cofactor tetrahydrobiopterin (BH4) is an essential requirement for the delivery of an electron to the intermediate in the catalytic cycle of NOS.
R-HSA-202129 (Reactome) HSP90 interacts with the amino terminus of eNOS (amino acids 442-600) and facilitates displacement of caveolin by calmodulin (CaM).
R-HSA-202132 (Reactome) Once depalmitoylated, it's proposed that eNOS is displaced from the plasma membrane and redistributed to other intracellular membranes, including the Golgi, where re-palmitoylation occurs. The mechanism of transport from the plasma membrane is still unknown.
R-HSA-202137 (Reactome) AKT1 is recruited to the M domain of HSP90.
R-HSA-202144 (Reactome) HSP90 facilitates the CaM-induced displacement of caveolin from eNOS.
R-HSA-203553 (Reactome) NOSIP (eNOS interacting protein) binds to the carboxyl-terminal region of the eNOS oxygenase domain. Note that the eNOS binding sites for caveolin and NOSIP overlap.
R-HSA-203565 (Reactome) NOSTRIN interacts with the actin nucleation promoting factor N-WASP by means of its SH3 domain.
R-HSA-203567 (Reactome) DHHC-21 is a Golgi-localized acyl transferase that palmitoylates eNOS, which targets eNOS to plasmalemmal caveolae. Localization to this microdomain is likely to optimize eNOS activation and the extracellular release of nitric oxide.
R-HSA-203611 (Reactome) A glycine residue (Gly2) at the N-terminus of eNOS is myristoylated, providing membrane localization.
R-HSA-203613 (Reactome) Increases in intracellular calcium and calmodulin stimulate depalmitoylation of eNOS by acyl protein thioesterase 1, which displaces eNOS from the membrane. This might be a mechanism to downregulate NO production following intense stimuli.
R-HSA-203625 (Reactome) NOSTRIN translocates eNOS from the plasma membrane to intracellular vesicular structures. NOSTRIN internalization of eNOS is proposed to occur via vesicle fission and caveolar transport through cooperation with dynamin and N-WASP.
R-HSA-203662 (Reactome) NOSTRIN binds to dynamin via its SH3 domain.
R-HSA-203680 (Reactome) NOSIP promotes translocation of eNOS from the plasma membrane to intracellular sites, thereby uncoupling eNOS from plasma membrane caveolae and inhibiting NO synthesis. eNOS appears to be shifted to intracellular sites that colocalize with Golgi and/or cytoskeletal marker proteins.
R-HSA-203700 (Reactome) Palymitoylated, myristoylated eNOS forms a dimer and is transported from the Golgi to the plasma membrane. Transport is thought to be mediated by intracellular vesicles, but the details remain unknown.
R-HSA-203712 (Reactome) Caveolin-1 is the primary negative regulatory protein for eNOS. Caveolin-1 binding to eNOS compromises its ability to bind Calmodulin (CaM), thereby inhibiting enzyme activity. The major binding region of caveolin-1 for eNOS is within amino acids 60-101 and to a lesser extent, amino acids 135-178.
R-HSA-203716 (Reactome) eNOS interacts with the SH3 domain of NOSTRIN (positions 434-506). Caveolin-1 also binds directly to NOSTRIN (residues 323-434), thus allowing formation of a ternary complex.
R-HSA-5340214 (Reactome) Vertebrates possess multiple respiratory globins that differ in structure, function, and tissue distribution. Three different globins have been described so far: hemoglobin facilitates oxygen transport in blood, myoglobin mediates oxygen transport and storage in the muscle and neuroglobin has a yet unidentified function in nerve cells. A fourth globin has been identified in mouse, human and zebrafish. It is ubiquitously expressed in human tissue and therefore called cytoglobin (CYGB) (Burmester et al. 2002, Trent & Hargrove 2002). Unlike the specific expression patterns of Hb and Mb, CYGB is found in vascular smooth muscle, fibroblasts and cardiomyocytes. CYGB functions as a homodimer (Hamdane et al. 2003) and is localised to the cytosol of these cells where its O2 loading and unloading ability within a narrow O2 tension range makes it an ideal protein for O2 storage, especially during hypoxia (Fago et al. 2004).
R-HSA-5340226 (Reactome) Vertebrates possess multiple respiratory globins that differ in structure, function, and tissue distribution. Three different globins have been described so far: haemoglobin facilitates oxygen transport in blood, myoglobin mediates oxygen transport and storage in the muscle and neuroglobin has a yet unidentified function in nerve cells. A fourth globin has been identified in mouse, human and zebrafish. It is ubiquitously expressed in human tissue and therefore called cytoglobin (CYGB) (Trent & Hargrove 2002). Unlike the specific expression patterns of Hb and Mb, CYGB is found in vascular smooth muscle, fibroblasts and cardiomyocytes. CYGB functions as a homodimer (Hamdane et al. 2003) and is localised to the cytosol. As well as oxygen binding capability, CYGB possesses nitric oxide dioxygenase activity (Halligan et al. 2009), a common feature amongst the globin family (Smagghe et al. 2008). CYGB consumes NO through the dioxygenase pathway, which regulates cell respiration and proliferation (Smagghe et al. 2008). O2 binds to the ferric form of CYGB (CYGB-Fe2+:O2). During NO dioxygenation, CYGB is reduced to the ferrous form (CYGB-Fe3+) (Gardner 2005).
R-HSA-5693373 (Reactome) N(G),N(G)-dimethylarginine dimethylaminohydrolases 1 and 2 (DDAH1 and 2) play a role in the regulation of nitric oxide generation. They can hydrolyse an endogenous inhibitor of nitric oxide synthase (NOS), N(omega),N(omega)-dimethyl-L-arginine (ADMA) to dimethylamine (DMA) and L-citrulline (L-Cit) (Forbes et al. 2008, Wang et al. 2009, Cillero-Pastor et al. 2012).
ZDHHC21mim-catalysisR-HSA-203567 (Reactome)
eNOS:CaM:HSP90:p-AKT1ArrowR-HSA-202137 (Reactome)
eNOS:CaM:HSP90:p-AKT1R-HSA-202111 (Reactome)
eNOS:CaM:HSP90ArrowR-HSA-202144 (Reactome)
eNOS:CaM:HSP90R-HSA-202137 (Reactome)
eNOS:Caveolin-1:CaM:HSP90ArrowR-HSA-202129 (Reactome)
eNOS:Caveolin-1:CaM:HSP90R-HSA-202144 (Reactome)
eNOS:Caveolin-1:CaMArrowR-HSA-202110 (Reactome)
eNOS:Caveolin-1:CaMR-HSA-202129 (Reactome)
eNOS:Caveolin-1:NOSTRIN complexArrowR-HSA-203716 (Reactome)
eNOS:Caveolin-1:NOSTRIN complexR-HSA-203662 (Reactome)
eNOS:Caveolin-1:NOSTRIN:Dynamin-2ArrowR-HSA-203662 (Reactome)
eNOS:Caveolin-1:NOSTRIN:Dynamin-2R-HSA-203565 (Reactome)
eNOS:Caveolin-1:NOSTRIN:dynamin-2:N-WASPArrowR-HSA-203565 (Reactome)
eNOS:Caveolin-1:NOSTRIN:dynamin-2:N-WASPArrowR-HSA-203625 (Reactome)
eNOS:Caveolin-1:NOSTRIN:dynamin-2:N-WASPR-HSA-203625 (Reactome)
eNOS:Caveolin-1ArrowR-HSA-203712 (Reactome)
eNOS:Caveolin-1R-HSA-202110 (Reactome)
eNOS:Caveolin-1R-HSA-203716 (Reactome)
eNOS:NOSIPArrowR-HSA-203553 (Reactome)
eNOS:NOSIPArrowR-HSA-203680 (Reactome)
eNOS:NOSIPR-HSA-203680 (Reactome)
myristoylated eNOS dimerArrowR-HSA-202132 (Reactome)
myristoylated eNOS dimerArrowR-HSA-203613 (Reactome)
myristoylated eNOS dimerR-HSA-202132 (Reactome)
p-S1177-eNOS:CaM:HSP90:p-AKT1:BH2ArrowR-HSA-1497796 (Reactome)
p-S1177-eNOS:CaM:HSP90:p-AKT1:BH2mim-catalysisR-HSA-1497810 (Reactome)
p-S1177-eNOS:CaM:HSP90:p-AKT1:BH4ArrowR-HSA-1497784 (Reactome)
p-S1177-eNOS:CaM:HSP90:p-AKT1:BH4R-HSA-1497796 (Reactome)
p-S1177-eNOS:CaM:HSP90:p-AKT1:BH4mim-catalysisR-HSA-202127 (Reactome)
p-S1177-eNOS:CaM:HSP90:p-AKT1ArrowR-HSA-202111 (Reactome)
p-S1177-eNOS:CaM:HSP90:p-AKT1R-HSA-1497784 (Reactome)
p-SPR dimermim-catalysisR-HSA-1497869 (Reactome)
p-T308,S473-AKT1R-HSA-202137 (Reactome)

myristoylated eNOS

ArrowR-HSA-203700 (Reactome)

myristoylated eNOS

R-HSA-203553 (Reactome)

myristoylated eNOS

R-HSA-203613 (Reactome)

myristoylated eNOS

R-HSA-203712 (Reactome)
sepiapterinR-HSA-1497869 (Reactome)

Personal tools