Beta-2 adrenergic receptor

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Identifiers
Aliases
External IDsGeneCards: [1]
Orthologs
SpeciesHumanMouse
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The beta-2 adrenergic receptor (β2 adrenoreceptor), also known as ADRB2, is a cell membrane-spanning beta-adrenergic receptor that interacts with (binds) epinephrine, a hormone and neurotransmitter (ligand synonym, adrenaline) whose signaling, via adenylate cyclase stimulation through trimeric Gs proteins, increased cAMP, and downstream L-type calcium channel interaction, mediates physiologic responses such as smooth muscle relaxation and bronchodilation.[1]

The official symbol for the human gene encoding the β2 adrenoreceptor is ADRB2.[2]

Gene

The ADRB2 gene is intronless. Different polymorphic forms, point mutations, and/or downregulation of this gene are associated with nocturnal asthma, obesity and type 2 diabetes.[3]

Structure

The 3D crystallographic structure (see figure and links to the right) of the β2-adrenergic receptor has been determined[4][5][6] by making a fusion protein with lysozyme to increase the hydrophilic surface area of the protein for crystal contacts. An alternative method, involving production of a fusion protein with an agonist, supported lipid-bilayer co-crystallization and generation of a 3.5 Å resolution structure.[7]

Mechanism

This receptor is directly associated with one of its ultimate effectors, the class C L-type calcium channel CaV1.2. This receptor-channel complex is coupled to the Gs G protein, which activates adenylyl cyclase, catalysing the formation of cyclic adenosine monophosphate (cAMP) which then activates protein kinase A, and counterbalancing phosphatase PP2A. Protein kinase A then goes on to phosphorylate (and thus inactivate) myosin light-chain kinase, which causes smooth muscle relaxation, accounting for the vasodilatory effects of beta 2 stimulation. The assembly of the signaling complex provides a mechanism that ensures specific and rapid signaling. A two-state biophysical and molecular model has been proposed to account for the pH and REDOX sensitivity of this and other GPCRs.[8]

Beta-2 adrenergic receptors have also been found to couple with Gi, possibly providing a mechanism by which response to ligand is highly localized within cells. In contrast, Beta-1 adrenergic receptors are coupled only to Gs, and stimulation of these results in a more diffuse cellular response.[9] This appears to be mediated by cAMP induced PKA phosphorylation of the receptor.[10]

Function

Actions of the β2 receptor include:

Muscular System

Function Tissue Biological Role
Smooth muscle relaxation in: GI tract (decreases motility) Inhibition of digestion
Bronchi[11] Facilitation of respiration. Hence, beta-2 agonists can be useful in treating asthma.
Detrusor urinae muscle of bladder wall[12][13] This effect is stronger than the alpha-1 receptor effect of contraction. Inhibition of need for micturition
Uterus Inhibition of labor
Seminal tract[14]
Increased perfusion and vasodilation Blood vessels and arteries to skeletal muscle including the smaller coronary arteries[15] and hepatic artery Facilitation of muscle contraction and motility
Increased mass and contraction speed Striated muscle[14]
Insulin and glucagon secretion Pancreas[16] Increased blood glucose and uptake by skeletal muscle
Glycogenolysis[14]
Tremor Motor nerve terminals.[14] Tremor is mediated by PKA mediated facilitation of presynaptic Ca2+ influx leading to acetylcholine release.
Legend
  The function facilitates the fight-or-flight response.

Circulatory system

Eye

In the normal eye, beta-2 stimulation by salbutamol increases intraocular pressure via net:

In glaucoma, drainage is reduced ( open-angle glaucoma) or blocked completely (closed-angle glaucoma). In such cases, beta-2 stimulation with its consequent increase in humour production is highly contra-indicated, and conversely, a topical beta-2 antagonist such as timolol may be employed.

Digestive system

Other

  • Inhibit histamine-release from mast cells.
  • Increase protein content of secretions from lacrimal glands.
  • Receptor also present in cerebellum.
  • Bronchiole dilation (targeted while treating asthma attacks)
  • Involved in brain - immune - communication [18]

Agonists

Beta-2 adrenergic receptor
Transduction mechanismsPrimary: Gs
Secondary: Gi/o
Primary endogenous agonistsepinephrine, norepinephrine
Agonistsisoprenaline, salbutamol, salmeterol, others
Antagonistscarvedilol, propranolol, labetalol, others
Inverse agonistsN/A
Positive allosteric modulatorsZn2+ (low concentrations)
Negative allosteric modulatorsZn2+ (high concentrations)
External resources
IUPHAR/BPS29
DrugBankP07550
HMDBHMDBP01634
Main article: Beta2-adrenergic agonist

Spasmolytics used in asthma and COPD

Tocolytic agents

β2 agonists used for other purposes

Antagonists

(Beta blockers)

* denotes selective antagonist to the receptor.

Interactions

Beta-2 adrenergic receptor has been shown to interact with:

See also

References

  1. ↑ Johnson M (January 2006). "Molecular mechanisms of beta(2)-adrenergic receptor function, response, and regulation". The Journal of Allergy and Clinical Immunology. 117 (1): 18–24, quiz 25. doi:10.1016/j.jaci.2005.11.012. PMID 16387578.
  2. ↑ "Entrez Gene: ADRB2 adrenoceptor beta 2, surface". Retrieved 8 February 2015.
  3. ↑ "Entrez Gene: ADRB2 adrenergic, beta-2-, receptor, surface".
  4. ↑ Cherezov V, Rosenbaum DM, Hanson MA, Rasmussen SG, Thian FS, Kobilka TS, Choi HJ, Kuhn P, Weis WI, Kobilka BK, Stevens RC (2007). "High-resolution crystal structure of an engineered human β2-adrenergic G protein-coupled receptor". Science. 318 (5854): 1258–65. Bibcode:2007Sci...318.1258C. doi:10.1126/science.1150577. PMC 2583103. PMID 17962520.
  5. ↑ Rosenbaum DM, Cherezov V, Hanson MA, Rasmussen SG, Thian FS, Kobilka TS, Choi HJ, Yao XJ, Weis WI, Stevens RC, Kobilka BK (2007). "GPCR engineering yields high-resolution structural insights into β2-adrenergic receptor function". Science. 318 (5854): 1266–73. Bibcode:2007Sci...318.1266R. doi:10.1126/science.1150609. PMID 17962519.
  6. ↑ Rasmussen SG, Choi HJ, Rosenbaum DM, Kobilka TS, Thian FS, Edwards PC, Burghammer M, Ratnala VR, Sanishvili R, Fischetti RF, Schertler GF, Weis WI, Kobilka BK (Nov 2007). "Crystal structure of the human beta2 adrenergic G-protein-coupled receptor". Nature. 450 (7168): 383–7. Bibcode:2007Natur.450..383R. doi:10.1038/nature06325. PMID 17952055.
  7. ↑ Liszewski, Kathy (1 October 2015). "Dissecting the Structure of Membrane Proteins". Genetic Engineering & Biotechnology News (paper). 35 (17): 16.(subscription required)
  8. ↑ Rubenstein LA, Zauhar RJ, Lanzara RG (Dec 2006). "Molecular dynamics of a biophysical model for beta2-adrenergic and G protein-coupled receptor activation". Journal of Molecular Graphics & Modelling. 25 (4): 396–409. doi:10.1016/j.jmgm.2006.02.008. PMID 16574446.
  9. ↑ Chen-Izu Y, Xiao RP, Izu LT, Cheng H, Kuschel M, Spurgeon H, Lakatta EG (Nov 2000). "G(i)-dependent localization of beta(2)-adrenergic receptor signaling to L-type Ca(2+) channels". Biophysical Journal. 79 (5): 2547–56. Bibcode:2000BpJ....79.2547C. doi:10.1016/S0006-3495(00)76495-2. PMC 1301137. PMID 11053129.
  10. ↑ Zamah AM, Delahunty M, Luttrell LM, Lefkowitz RJ (Aug 2002). "Protein kinase A-mediated phosphorylation of the beta 2-adrenergic receptor regulates its coupling to Gs and Gi. Demonstration in a reconstituted system". The Journal of Biological Chemistry. 277 (34): 31249–56. doi:10.1074/jbc.M202753200. PMID 12063255.
  11. ↑ 11.0 11.1 11.2 11.3 11.4 11.5 Fitzpatrick D, Purves D, Augustine G (2004). "Table 20:2". Neuroscience (Third ed.). Sunderland, Mass: Sinauer. ISBN 0-87893-725-0.
  12. ↑ von Heyden B, Riemer RK, Nunes L, Brock GB, Lue TF, Tanagho EA (1995). "Response of guinea pig smooth and striated urethral sphincter to cromakalim, prazosin, nifedipine, nitroprusside, and electrical stimulation". Neurourology and Urodynamics. 14 (2): 153–68. doi:10.1002/nau.1930140208. PMID 7540086.
  13. ↑ Moro C, Tajouri L, Chess-Williams R (January 2013). "Adrenoceptor function and expression in bladder urothelium and lamina propria". Urology. 81 (1): 211.e1–7. doi:10.1016/j.urology.2012.09.011. PMID 23200975.
  14. ↑ 14.0 14.1 14.2 14.3 14.4 Rang HP (2003). Pharmacology. Edinburgh: Churchill Livingstone. ISBN 0-443-07145-4. Page 163
  15. ↑ Rang HP (2003). Pharmacology. Edinburgh: Churchill Livingstone. p. 270. ISBN 0-443-07145-4.
  16. ↑ Philipson, L. H. (December 2002). "beta-Agonists and metabolism". The Journal of Allergy and Clinical Immunology. 110 (6 Suppl): S313–317. doi:10.1067/mai.2002.129702. ISSN 0091-6749. PMID 12464941.
  17. ↑ Philipson, L. H. (December 2002). "beta-Agonists and metabolism". The Journal of Allergy and Clinical Immunology. 110 (6 Suppl): S313–317. doi:10.1067/mai.2002.129702. ISSN 0091-6749. PMID 12464941.
  18. ↑ Elenkov IJ, Wilder RL, Chrousos GP, Vizi ES (Dec 2000). "The sympathetic nerve--an integrative interface between two supersystems: the brain and the immune system". Pharmacological Reviews. 52 (4): 595–638. PMID 11121511.
  19. ↑ Matera MG, Cazzola M (2007). "ultra-long-acting beta2-adrenoceptor agonists: an emerging therapeutic option for asthma and COPD?". Drugs. 67 (4): 503–15. doi:10.2165/00003495-200767040-00002. PMID 17352511.
  20. ↑ Fan G, Shumay E, Wang H, Malbon CC (Jun 2001). "The scaffold protein gravin (cAMP-dependent protein kinase-anchoring protein 250) binds the beta 2-adrenergic receptor via the receptor cytoplasmic Arg-329 to Leu-413 domain and provides a mobile scaffold during desensitization". The Journal of Biological Chemistry. 276 (26): 24005–14. doi:10.1074/jbc.M011199200. PMID 11309381.
  21. ↑ Shih M, Lin F, Scott JD, Wang HY, Malbon CC (Jan 1999). "Dynamic complexes of beta2-adrenergic receptors with protein kinases and phosphatases and the role of gravin". The Journal of Biological Chemistry. 274 (3): 1588–95. doi:10.1074/jbc.274.3.1588. PMID 9880537.
  22. ↑ McVey M, Ramsay D, Kellett E, Rees S, Wilson S, Pope AJ, Milligan G (Apr 2001). "Monitoring receptor oligomerization using time-resolved fluorescence resonance energy transfer and bioluminescence resonance energy transfer. The human delta -opioid receptor displays constitutive oligomerization at the cell surface, which is not regulated by receptor occupancy". The Journal of Biological Chemistry. 276 (17): 14092–9. doi:10.1074/jbc.M008902200. PMID 11278447.
  23. ↑ Karoor V, Wang L, Wang HY, Malbon CC (Dec 1998). "Insulin stimulates sequestration of beta-adrenergic receptors and enhanced association of beta-adrenergic receptors with Grb2 via tyrosine 350". The Journal of Biological Chemistry. 273 (49): 33035–41. doi:10.1074/jbc.273.49.33035. PMID 9830057.
  24. ↑ Temkin P, Lauffer B, Jäger S, Cimermancic P, Krogan NJ, von Zastrow M (Jun 2011). "SNX27 mediates retromer tubule entry and endosome-to-plasma membrane trafficking of signalling receptors". Nature Cell Biology. 13 (6): 715–21. doi:10.1038/ncb2252. PMC 3113693. PMID 21602791.
  25. ↑ Karthikeyan S, Leung T, Ladias JA (May 2002). "Structural determinants of the Na+/H+ exchanger regulatory factor interaction with the beta 2 adrenergic and platelet-derived growth factor receptors". The Journal of Biological Chemistry. 277 (21): 18973–8. doi:10.1074/jbc.M201507200. PMID 11882663.
  26. ↑ Hall RA, Ostedgaard LS, Premont RT, Blitzer JT, Rahman N, Welsh MJ, Lefkowitz RJ (Jul 1998). "A C-terminal motif found in the beta2-adrenergic receptor, P2Y1 receptor and cystic fibrosis transmembrane conductance regulator determines binding to the Na+/H+ exchanger regulatory factor family of PDZ proteins". Proceedings of the National Academy of Sciences of the United States of America. 95 (15): 8496–501. Bibcode:1998PNAS...95.8496H. doi:10.1073/pnas.95.15.8496. PMC 21104. PMID 9671706.
  27. ↑ Hall RA, Premont RT, Chow CW, Blitzer JT, Pitcher JA, Claing A, Stoffel RH, Barak LS, Shenolikar S, Weinman EJ, Grinstein S, Lefkowitz RJ (Apr 1998). "The beta2-adrenergic receptor interacts with the Na+/H+-exchanger regulatory factor to control Na+/H+ exchange". Nature. 392 (6676): 626–30. Bibcode:1998Natur.392..626H. doi:10.1038/33458. PMID 9560162.

Further reading

External links

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