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Beta-2 adrenergic receptor

From Wikipedia, the free encyclopedia
ADRB2
Available structures
PDBOrtholog search: PDBe RCSB
Identifiers
AliasesADRB2, ADRB2R, ADRBR, B2AR, BAR, BETA2AR, adrenoceptor beta 2
External IDsOMIM: 109690; MGI: 87938; HomoloGene: 30948; GeneCards: ADRB2; OMA:ADRB2 - orthologs
Orthologs
SpeciesHumanMouse
Entrez

154

11555

Ensembl

ENSG00000169252

ENSMUSG00000045730

UniProt

P07550

P18762

RefSeq (mRNA)

NM_000024

NM_007420

RefSeq (protein)

NP_000015

NP_031446

Location (UCSC)Chr 5: 148.83 – 148.83 MbChr 18: 62.31 – 62.31 Mb
PubMed search[3][4]
Wikidata
View/Edit HumanView/Edit Mouse

The beta-2 adrenergic receptor (β2 adrenoreceptor), also known as ADRB2, is a cell membrane-spanning beta-adrenergic receptor that binds epinephrine (adrenaline), a hormone and neurotransmitter whose signaling, via adenylate cyclase stimulation through trimeric Gs proteins, increases cAMP, and, via downstream L-type calcium channel interaction, mediates physiologic responses such as smooth muscle relaxation and bronchodilation.[5]

Robert J. Lefkowitz[6] and Brian Kobilka[7] studied beta 2 adrenergic receptor as a model system which earned them the 2012 Nobel Prize in Chemistry[8] “for groundbreaking discoveries that reveal the inner workings of an important family of such receptors: G-protein-coupled-receptors”.

The official symbol for the human gene encoding the β2 adrenoreceptor is ADRB2.[9]

Gene

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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.[10]

Structure

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The 3D crystallographic structure (see figure and links to the right) of the β2-adrenergic receptor has been determined[11][12][13] 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.[14]

The crystal structure of the β2Adrenergic Receptor-Gs protein complex was solved in 2011. The largest conformational changes in the β2AR include a 14 Å outward movement at the cytoplasmic end of transmembrane segment 6 (TM6) and an alpha helical extension of the cytoplasmic end of TM5.[15]

Mechanism

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This receptor is directly associated with one of its ultimate effectors, the class C L-type calcium channel CaV1.2.[citation needed] 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.[16]

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.[17] This appears to be mediated by cAMP induced PKA phosphorylation of the receptor.[18] Interestingly, Beta-2 adrenergic receptor was observed to localize exclusively to the T-tubular network of adult cardiomyocytes, as opposed to Beta-1 adrenergic receptor, which is observed also on the outer plasma membrane of the cell [19]

Function

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Function Tissue Biological Role
Smooth muscle relaxation in: GI tract (decreases motility) Inhibition of digestion
Bronchi[20] Facilitation of respiration.
Detrusor urinae muscle of bladder wall[21][22] This effect is stronger than the alpha-1 receptor effect of contraction. Inhibition of need for micturition
Uterus Inhibition of labor
Seminal tract[23]
Increased perfusion and vasodilation Blood vessels and arteries to skeletal muscle including the smaller coronary arteries[24] and hepatic artery Facilitation of muscle contraction and motility
Increased mass and contraction speed Striated muscle[23]
Insulin and glucagon secretion Pancreas[25] Increased blood glucose and uptake by skeletal muscle
Glycogenolysis[23]
Tremor Motor nerve terminals.[23] Tremor is mediated by PKA mediated facilitation of presynaptic Ca2+ influx leading to acetylcholine release.
Legend
  The function facilitates the fight-or-flight response.

Musculoskeletal system

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Activation of the β2 adrenoreceptor with long-acting agents such as oral clenbuterol and intravenously-infused albuterol results in skeletomuscular hypertrophy and anabolism.[26][27] The comprehensive anabolic, lipolytic, and ergogenic effects of long-acting β2 agonists such as clenbuterol render them frequent targets as performance-enhancing drugs in athletes.[28] Consequently, such agents are monitored for and generally banned by WADA (World Anti-Doping Agency) with limited permissible usage under therapeutic exemptions; clenbuterol and other β2 adrenergic agents remain banned not as a beta-agonist, but rather an anabolic agent. These effects are largely attractive within agricultural contexts insofar that β2 adrenergic agents have seen notable extra-label usage in food-producing animals and livestock. While many countries including the United States have prohibited extra-label usage in food-producing livestock, the practice is still observed in many countries. [29][30]

Circulatory system

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Eye

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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

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Other

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  • 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 [31]

Ligands

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Agonists

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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

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Tocolytic agents

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β2 agonists used for other purposes

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Antagonists

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(Beta blockers)

* denotes selective antagonist to the receptor.

Allosteric modulators

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  • compound-6FA,[33] PAM at intracellular binding site
  • Cellular swelling [34]

Interactions

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

See also

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References

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  1. ^ a b c GRCh38: Ensembl release 89: ENSG00000169252 – Ensembl, May 2017
  2. ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000045730 – Ensembl, May 2017
  3. ^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  4. ^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  5. ^ 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.
  6. ^ "The Nobel Prize in Chemistry 2012". NobelPrize.org. Retrieved 2021-07-04.
  7. ^ "The Nobel Prize in Chemistry 2012". NobelPrize.org. Retrieved 2021-07-04.
  8. ^ "The Nobel Prize in Chemistry 2012". NobelPrize.org. Retrieved 2021-07-04.
  9. ^ "Entrez Gene: ADRB2 adrenoceptor beta 2, surface". Retrieved 8 February 2015.
  10. ^ "Entrez Gene: ADRB2 adrenergic, beta-2-, receptor, surface".
  11. ^ 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.
  12. ^ 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. S2CID 1559802.
  13. ^ 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. S2CID 4407117.
  14. ^ Liszewski K (1 October 2015). "Dissecting the Structure of Membrane Proteins". Genetic Engineering & Biotechnology News (paper). 35 (17): 16. doi:10.1089/gen.35.07.09.(subscription required)
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  18. ^ 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.
  19. ^ Bathe-Peters M, Gmach P, Boltz HH, Einsiedel J, Gotthardt M, Hübner H, et al. (June 2021). "Visualization of β-adrenergic receptor dynamics and differential localization in cardiomyocytes". Proceedings of the National Academy of Sciences of the United States of America. 118 (23): e2101119118. Bibcode:2021PNAS..11801119B. doi:10.1073/pnas.2101119118. ISSN 0027-8424. PMC 8201832. PMID 34088840.
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  22. ^ 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.
  23. ^ a b c d e Rang HP (2003). Pharmacology. Edinburgh: Churchill Livingstone. ISBN 978-0-443-07145-4. Page 163
  24. ^ Rang HP (2003). Pharmacology. Edinburgh: Churchill Livingstone. p. 270. ISBN 978-0-443-07145-4.
  25. ^ a b Philipson LH (December 2002). "beta-Agonists and metabolism". The Journal of Allergy and Clinical Immunology. 110 (6 Suppl): S313-7. doi:10.1067/mai.2002.129702. PMID 12464941.
  26. ^ Choo JJ, Horan MA, Little RA, Rothwell NJ (July 1992). "Anabolic effects of clenbuterol on skeletal muscle are mediated by beta 2-adrenoceptor activation". The American Journal of Physiology. 263 (1 Pt 1): E50-6. doi:10.1152/ajpendo.1992.263.1.E50. PMID 1322047.
  27. ^ Kamalakkannan G, Petrilli CM, George I, LaManca J, McLaughlin BT, Shane E, et al. (April 2008). "Clenbuterol increases lean muscle mass but not endurance in patients with chronic heart failure". The Journal of Heart and Lung Transplantation. 27 (4): 457–61. doi:10.1016/j.healun.2008.01.013. PMID 18374884.
  28. ^ Davis E, Loiacono R, Summers RJ (June 2008). "The rush to adrenaline: drugs in sport acting on the beta-adrenergic system". British Journal of Pharmacology. 154 (3): 584–97. doi:10.1038/bjp.2008.164. PMC 2439523. PMID 18500380.
  29. ^ "Clenbuterol" (PDF). Drug and Chemical Evaluation Section. Drug Enforcement Agency. Retrieved 15 November 2021.
  30. ^ "Food and Drugs - ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS". U.S. Food and Drug Administration. Retrieved 15 November 2021.
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  32. ^ 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. S2CID 46976912.
  33. ^ Liu X, Masoudi A, Kahsai AW, Huang LY, Pani B, Staus DP, et al. (June 2019). "Mechanism of β2AR regulation by an intracellular positive allosteric modulator". Science. 364 (6447): 1283–1287. Bibcode:2019Sci...364.1283L. doi:10.1126/science.aaw8981. PMC 6705129. PMID 31249059.
  34. ^ Sirbu A, Bathe-Peters M, Kumar J, Inoue A, Lohse MJ, Annibale P (August 2024). "Cell swelling enhances ligand-driven β-adrenergic signaling". Nature Communications. 15 (1): 1–12. doi:10.1038/s41467-024-52191-y. PMC 11379887.
  35. ^ 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.
  36. ^ 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.
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Further reading

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