5-HT2A receptor

The mammalian 5-HT_2A receptor is a subtype of the 5-HT₂ receptor which belongs to the serotonin receptor family and is a G protein coupled receptor (GPCR).cite journal | author = Cook EH, Fletcher KE, Wainwright M, Marks N, Yan SY, Leventhal BL | title = Primary structure of the human platelet serotonin 5-HT2A receptor: identity with frontal cortex serotonin 5-HT_2A receptor | journal = J. Neurochem. | volume = 63 | issue = 2 | pages = 465–9 | year = 1994 | month = August | pmid = 8035173 | doi = 10.1046/j.1471-4159.1994.63020465.x | url = | issn = ] This is the main excitatory receptor subtype among the GPCRs for serotonin (5-HT), although 5-HT_2A may also have an inhibitory effect on certain areas such as the visual cortex and the orbitofrontal cortex. This receptor was given importance first as the target of psychedelic drugs like LSD. Later it came back to prominence because it was also found to be mediating, at least partly, the action of many antipsychotic drugs, especially the atypical ones.

5-HT_2A also happens to be a necessary receptor for the spread of the human polyoma virus called JC virus.cite journal | author = Elphick GF, Querbes W, Jordan JA, Gee GV, Eash S, Manley K, Dugan A, Stanifer M, Bhatnagar A, Kroeze WK, Roth BL, Atwood WJ | title = The human polyomavirus, JCV, uses serotonin receptors to infect cells | journal = Science | volume = 306 | issue = 5700 | pages = 1380–3 | year = 2004 | pmid = 15550673 | doi = 10.1126/science.1103492 | issn = ]

History

Serotonin receptors were split into two classes by Gaddum and Picarelli when it was discovered that some of the serotonin-induced changes in the gut could be blocked by morphine, whilst the remainder of the response was inhibited by dibenzyline leading to the naming of M and D receptors respectively. 5-HT_2A is thought to correspond to what was originally described as D subtype of 5-HT receptors by Gaddum and Picarelli [Chapter 11, Goodman & Gilman's The Pharmacological Basis of Therapeutics, 11th Edition ] . In the pre-molecular-cloning era when radioligand binding and displacement was the only major tool, spiperone and LSD were shown to label two different serotonin receptors, and neither of them displaced morphine, leading to naming of the 5-HT₁, 5-HT₂ and 5-HT₃ receptors, corresponding to high affinity sites from LSD, spiperone and morphine respectively (?). Later it was shown that the 5-HT₂ was very close to 5-HT_1C and thus were clubbed together, renaming the 5-HT₂ into 5-HT_2A. Thus the 5-HT₂ receptor family is comprised of three separate molecular entities: the 5-HT_2A (erstwhile 5-HT₂ or D), the 5-HT_2B (erstwhile 5-HT_2F) and the 5-HT_2C (erstwhile 5-HT_1C) receptors.cite journal |author=Hoyer D, Hannon J, Martin G |title=Molecular, pharmacological and functional diversity of 5-HT receptors |journal=Pharmacol Biochem Behav |volume=71 |issue=4 |pages=533–54 |year=2002 |pmid=11888546 |doi=10.1016/S0091-3057(01)00746-8]

Distribution

5-HT_2A is expressed widely throughout the central nervous system (CNS).It is expressed near most of the serotoninergic terminal rich areas, including neocortex (mainly prefrontal, parietal, and somatosensory cortex) and olfactory tubercle. There are especially high concentrations of this receptor on the apical dendrites of pyramidal cells in layer V of the cortex that may modulate cognitive processes. The protein has also been found in the Golgi cells of the granular layer in the rat cerebellum, [Cite journal
author = Frederik J. Geurts, Erik De Schutter and Jean-Pierre Timmermans
title = Localization of 5-HT_2A, 5-HT₃, 5-HT_5A and 5-HT₇ receptor-like immunoreactivity in the rat cerebellum
journal = Journal of Chemical Neuroanatomy
volume = 24
issue = 1
month = June
year = 2002
pages = 65–74
doi = 10.1016/S0891-0618(02)00020-0
url = http://www.tnb.ua.ac.be/publications/pub060/pub060.shtml] as well as in the Purkinje cells (also in the rat cerebellum). [Cite journal
author = Maeshima T, Shutoh F, Hamada S, Senzaki K, Hamaguchi-Hamada K, Ito R, Okado N.
title = Serotonin2A receptor-like immunoreactivity in rat cerebellar Purkinje cells
journal = Neurosci. Lett.
year = 1998
month = August
volume = 252
issue = 1
pages = 72–74
pmid = 9756362
doi = 10.1016/S0304-3940(98)00546-1] [Cite journal
author = Maeshima T, Shiga T, Ito R, Okado N.
title = Expression of serotonin2A receptors in Purkinje cells of the developing rat cerebellum
journal = Neurosci. Res.
year = 2004
month = December
volume = 50
issue = 4
pages = 411–417
pmid = 15567478
doi = 10.1016/j.neures.2004.08.010]

In the periphery, it is highly expressed in platelets and many cell types of the cardiovascularsystem, as well as in fibroblasts, and within neurons of the peripheral nervous system.

ignalling Cascade

The 5-HT_2A receptor is known primarily to couple to the Galphaq signal transduction pathway. Upon receptor stimulation with agonist, Gaphaq and beta-gamma subunits dissociate to initiate downstream effector pathways. Galphaq stimulates phospholipase C (PLC) activity, which subsequently promotes the release of diacylglycerol (DAG) and inositol triphosphate (IP3), which in turn stimulate protein kinase C (PKC) activity and Ca²⁺ release.cite journal | author = Urban JD, Clarke WP, von Zastrow M, Nichols DE, Kobilka B, Weinstein H, Javitch JA, Roth BL, Christopoulos A, Sexton PM, Miller KJ, Spedding M, Mailman RB | title = Functional selectivity and classical concepts of quantitative pharmacology | journal = J. Pharmacol. Exp. Ther. | volume = 320 | issue = 1 | pages = 1–13 | year = 2007 | pmid = 16803859 | doi = 10.1124/jpet.106.104463 | issn = ]

There are many additional signal cascade components that include the formation of arachidonic acid through PLA2 activity, activation of PLD, Rho/RhoK, and ERK pathway activation initiated by agonist stimulation of the receptor.Fact|date=November 2007

Effects

Effects of activation of the receptor include:
* CNS: neuronal excitation, behavioural effects, learning, anxiety
* smooth muscle: contraction (in gastrointestinal tract & bronchi)
* vasoconstriction / vasodilatation
* platelets: aggregation

Ligands

Functional selectivity

5-HT_2A-receptor ligands may differentially activate the transductional pathways (see above). Studies evaluated the activation of two effectors, PLC and PLA2, by means of their second messengers. Compounds displaying more pronounced functional selectivity are 2,5-DMA and 2C-N. The former induces IP accumulation without activating the PLA2 mediated response, while the latter elicits AA release without activating the PLC mediated response. cite journal | author = Moya PR, Berg KA, Gutiérrez-Hernandez MA, Sáez-Briones P, Reyes-Parada M, Cassels BK, Clarke WP | title = Functional selectivity of hallucinogenic phenethylamine and phenylisopropylamine derivatives at human 5-hydroxytryptamine 5-HT_2A and 5-HT_2C receptors | journal = J. Pharmacol. Exp. Ther. | volume = 321 | issue = 3 | pages = 1054–61 | year = 2007 | pmid = 17337633 | doi = 10.1124/jpet.106.117507 | issn = ]

Recent research has suggested potential signaling differences within the somatosensory cortex between 5-HT_2A agonists that produce headshakes in the mouse and those that do not.cite journal | author = González-Maeso J, Weisstaub NV, Zhou M, Chan P, Ivic L, Ang R, Lira A, Bradley-Moore M, Ge Y, Zhou Q, Sealfon SC, Gingrich JA | title = Hallucinogens recruit specific cortical 5-HT(2A) receptor-mediated signaling pathways to affect behavior | journal = Neuron | volume = 53 | issue = 3 | pages = 439–52 | year = 2007 | pmid = 17270739 | doi = 10.1016/j.neuron.2007.01.008 | issn = ] The difference in signal transduction between the two 5-HT_2A agonists serotonin and DOI may be due to the presence of the intracellular proteins called β-arrestins, more specifically arrestin beta 2.cite journal | author = Schmid CL, Raehal KM, Bohn LM | title = Agonist-directed signaling of the serotonin 2A receptor depends on beta-arrestin-2 interactions in vivo | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 105 | issue = 3 | pages = 1079–84 | year = 2008 | pmid = 18195357 | doi = 10.1073/pnas.0708862105 | issn = ] cite journal | author = Abbas A, Roth BL | title = Arresting serotonin | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 105 | issue = 3 | pages = 831–2 | year = 2008 | pmid = 18195368 | doi = 10.1073/pnas.0711335105 | issn = ]

Role of lipophilicity

A set of ligands were evaluated. For "agonists", a highly significant linear correlation was observed between binding affinity and lipophilicity. For ligands exhibiting partial agonist or antagonist properties, the lipophilicity was consistently higher than would be expected for an agonist of comparable affinity.cite journal | author = Parker MA, Kurrasch DM, Nichols DE | title = The role of lipophilicity in determining binding affinity and functional activity for 5-HT_2A receptor ligands | journal = Bioorg. Med. Chem. | volume = | issue = | pages = | year = 2008 | pmid = 18296055 | doi = 10.1016/j.bmc.2008.02.033 | issn = ]

"Agonists"

Activation of the 5-HT_2A receptor is necessary for the effects of the "classic" hallucinogens like LSD, psilocin and mescaline, which act as full or partial agonists at this receptor. Agonists acting at 5-HT_2A receptors located on the apical dendrites of pyramidal cells within regions of the prefrontal cortex are believed to mediate hallucinogenic activity.

;Full agonists
N-(2-hydroxybenzyl)-2C-I and its 2-methoxy-analog are highly potent agonists at the human 5-HT_2A receptor,cite journal
author = Braden MR, Parrish JC, Naylor JC, Nichols DE
title = Molecular interaction of serotonin 5-HT2A receptor residues Phe339(6.51) and Phe340(6.52) with superpotent N-benzyl phenethylamine agonists | journal = Mol. Pharmacol. | volume = 70 | issue = 6 | pages = 1956–64 | year = 2006 | pmid = 17000863 | doi = 10.1124/mol.106.028720 | issn = ] as are the benzocyclobutene derivative TCB-2 [McLean TH, Parrish JC, Braden MR, Marona-Lewicka D, Gallardo-Godoy A, Nichols DE. 1-Aminomethylbenzocycloalkanes: conformationally restricted hallucinogenic phenethylamine analogues as functionally selective 5-HT2A receptor agonists. "Journal of Medicinal Chemistry". 2006 Sep 21;49(19):5794-803. PMID 16970404] and the benzodifuran derivative Br-DFLY. [Chambers JJ, Kurrasch-Orbaugh DM, Parker MA, Nichols DE. Enantiospecific synthesis and pharmacological evaluation of a series of super-potent, conformationally restricted 5-HT(2A/2C) receptor agonists. "Journal of Medicinal Chemistry". 2001 Mar 15;44(6):1003-10. PMID 11300881]

;Partial agonists
Methysergide, a congener of methylergonovine, used in treatment of migraine blocks 5-HT_2A and 5-HT_2C receptors, but sometimes acts as partial agonist, in some preparations.

"Silent antagonists"

Although ergot alkaloids are mostly nonspecific 5-HT receptor antagonists, a few ergot derivatives such as metergoline bind preferentially to members of the 5-HT₂ receptor family. A number of antagonists for 5-HT_2A/2C are currently available but none are absolutely specific for 2A.Fact|date=April 2008
Ketanserin, the prototypic 5-HT_2A receptor antagonist potently blocks 5-HT_2A receptors, less potently blocks 5-HT_2C receptors, and has no significant effect on 5-HT₃ or 5-HT₄ receptors or any members of the 5-HT₁ receptor family. Thus discovery of Ketanserin was a landmark in the pharmacology of 5-HT₂ receptors. Ketanserin, though capable of blocking 5-HT induced platelet adhesion, however does not mediate its well known antihypertensive action through 5-HT₂ receptor family, but through its high affinity for alpha adrenergic receptors. It also has high affinity for H₁ histaminergic receptors. Compounds chemically related to ketanserin such as ritanserin are more selective 5-HT_2A receptor antagonists with low affinity for alpha-adrenergic receptors. However, ritanserin, like most other 5-HT_2A receptor antagonists, also potently inhibit 5-HT_2C receptors.

Nefazadone operates by blocking post-synaptic serotonin type-2A receptors and to a lesser extent by inhibiting pre-synaptic serotonin and norepinephrine (noradrenaline) reuptake.

Atypical antipsychotic drugs like Clozapine, Olanzapine, Quetiapine, risperidone are relatively potent antagonists of 5-HT_2A as are some of the lower potency old generation/typical antipsychotics. Other antagonists are MDL-100907 (prototype of another new series of 5-HT_2A antagonists) and Cyproheptadine. APD125, a new sleeping pill recently developed by Arena Pharmaceuticals and currently in Phase 2 trials, acts as a selective 5-HT_2A antagonist.

Pizotifen is a non-selective antagonist. cite book |author=Rang, H. P. |title=Pharmacology |publisher=Churchill Livingstone |location=Edinburgh |year=2003 |pages= |isbn=0-443-07145-4 |oclc= |doi= Page 187 ] 2-alkyl-4-aryl-tetrahydro-pyrimido-azepines are subtype selective antagonists (35g: 60-fold). [Cite journal
author = Brock T. Shireman, C. A. Dvorak, D. A. Rudolph, P. Bonaventure, D. Nepomuceno, L. Dvorak, K. L. Miller, T. W. Lovenberg, N. I. Carruthers NI
title = 2-Alkyl-4-aryl-pyrimidine fused heterocycles as selective 5-HT_2A antagonists
journal = Bioorg. Med. Chem. Lett.
year = 2008
month = March
volume = 18
issue = 6
pages = 2103–2108
pmid = 18282705
doi = 10.1016/j.bmcl.2008.01.090

]

Examples

Genetics

Chromosome 13.The 5-HT_2A receptors is coded by the "HTR2A" gene.In humans the gene is located on chromosome 13.The gene has previously been called just HTR2 until the description of two related genes "HTR2B" and "HTR2C".Several interesting polymorphisms have been identified for HTR2A:
A-1438G (rs6311),
C102T (rs6313) and
His452Tyr (rs6314).Many more polymorphisms exist for the gene.A 2006 paper listed 255. [Cite web
title = OSIRIS search results. Gene: HTR2A
url = http://bioinformatics.oxfordjournals.org/cgi/content/full/btl421v1/DC1/2 Supplementary material to article
* Cite journal
author = Julio Bonis, Laura Inés Furlong, and Ferran Sanz
title = OSIRIS: a tool for retrieving literature about sequence variants
journal = Bioinformatics
doi = 10.1093/bioinformatics/btl421
year = 2006
url = http://bioinformatics.oxfordjournals.org/cgi/content/abstract/btl421v1]

Associations with psychiatric disorders

Several studies have seen links between the -1438G/A polymorphism and mood disorders, such as bipolar disorderCite journal
author = Chee IS, Lee SW, Kim JL, Wang SK, Shin YO, Shin SC, Lee YH, Hwang HM, Lim MR
title = 5-HT_2A receptor gene promoter polymorphism -1438A/G and bipolar disorder
journal = Psychiatr. Genet.
volume = 11
issue = 3
pages = 111–114
year = 2001
pmid = 11702051
doi =
url = http://www.psychgenetics.com/pt/re/psychgen/abstract.00041444-200109000-00001.htm] and major depressive disorder.cite journal
author = Choi MJ, Lee HJ, Lee HJ, Ham BJ, Cha JH, Ryu SH, Lee MS
title = Association between major depressive disorder and the -1438A/G polymorphism of the serotonin 2A receptor gene
journal = Neuropsychobiology
volume = 49
issue = 1
pages = 38–41
year = 2004
pmid = 14730199
doi = 10.1159/000075337] A weak link with an odds ratio of 1.3 has been found between the T102C polymorphism and schizophrenia.cite journal
author = Williams J, Spurlock G, McGuffin P, Mallet J, Nöthen MM, Gill M, Aschauer H, Nylander PO, Macciardi F, Owen MJ
title = Association between schizophrenia and T102C polymorphism of the 5-hydroxytryptamine type 2a-receptor gene. European Multicentre Association Study of Schizophrenia (EMASS) Group
journal = The Lancet
volume = 347
issue = 9011
pages = 1294–1296
year = 1996
pmid = 8622505] This polymorphism has also been studied in relation to suicide attempts, with a study finding excess of the C/C genotypes among the suicide attempters. [Cite journal
author = Vaquero-Lorenzo C, Baca-Garcia E, Diaz-Hernandez M, Perez-Rodriguez MM, Fernandez-Navarro P, Giner L, Carballo JJ, Saiz-Ruiz J, Fernandez-Piqueras J, Baldomero EB, de Leon J, Oquendo MA
title = Association study of two polymorphisms of the serotonin-2A receptor gene and suicide attempts
journal = Am J Med Genet B Neuropsychiatr Genet
doi = 10.1002/ajmg.b.30642 Electronic publication: 2007 December 28]

These individual studies may, however, not give a full picture: A review from 2007 looking at the effect of different SNPs reported in separate studies stated that "genetic association studies of "HTR2A" gene variants with psychiatric disorders report conflicting and generally negative results" with no involvement, small or a not replicated role for the genetic variant of the gene. [Cite journal
author = Alessandro Serretti, Antonio Drago & Diana De Ronchi
title = HTR2A gene variants and psychiatric disorders: a review of current literature and selection of SNPs for future studies
journal = Current Medicinal Chemistry
volume = 14
issue = 19
pages = 2053–2059
year = 2007
month =
pmid = 17691947]

Treatment response

One study has found that genetic variations between individuals in the HTR2A gene may to some extent account for the difference in outcome of antidepressant treatment, so that patients suffering from major depressive disorder and treated with Citalopram may benefit more than others if they have one particular genotype.cite journal
author = McMahon FJ, Buervenich S, Charney D, Lipsky R, Rush AJ, Wilson AF, Sorant AJ, Papanicolaou GJ, Laje G, Fava M, Trivedi MH, Wisniewski SR, Manji H
title = Variation in the gene encoding the serotonin 2A receptor is associated with outcome of antidepressant treatment
journal = Am. J. Hum. Genet.
volume = 78
issue = 5
pages = 804–814
year = 2006
pmid = 16642436
doi = 10.1086/503820] In this study 768 single nucleotide polymorphism (SNP) across 68 genes were investigated and a SNP—termed rs7997012—in the second intron of the HTR2A gene showed significant association with treatment outcome.

Genetics seems also to be associated to some extent with the amount of adverse events in treatment of major depression disorder.cite journal
author = Laje G, Paddock S, Manji H, Rush AJ, Wilson AF, Charney D, McMahon FJ
title = Genetic markers of suicidal ideation emerging during citalopram treatment of major depression
journal = Am J Psychiatry
volume = 164
issue = 10
pages = 1530–1538
year = 2007
pmid = 17898344
doi = 10.1176/appi.ajp.2007.06122018] cite journal
author = Laje G, McMahon FJ
title = The pharmacogenetics of major depression: past, present, and future
journal = Biol. Psychiatry
volume = 62
issue = 11
pages = 1205–1207
year = 2007
pmid = 17949692
doi = 10.1016/j.biopsych.2007.09.016]

Neuroimaging

The 5-HT_2A receptors may be imaged with PET-scanners using the fluorine-18-altanserinCite journal
author = Lemaire C, Cantineau R, Guillaume M, Plenevaux A, Christiaens L
title = Fluorine-18-altanserin: a radioligand for the study of serotonin receptors with PET: radiolabeling and in vivo biologic behavior in rats
journal = Journal of Nuclear Medicine
volume = 32
issue = 12
pages = 2266–2272
year = 1991
pmid = 1744713
url = http://jnm.snmjournals.org/cgi/content/abstract/32/12/2266] and MDL 100,907Cite journal
author = Lundkvist C, Halldin C, Ginovart N, Nyberg S, Swahn CG, Carr AA, Brunner F, Lars Farde
title = ¹¹C-MDL 100907, a radioligland for selective imaging of 5-HT_2A receptors with positron emission tomography
journal = Life Sci.
volume = 58
issue = 10
pages = PL 187–192
year = 1996
pmid = 8602111
doi = 10.1016/0024-3205(96)00013-6]
radioligands that binds to the neuroreceptor, e.g., one study reported a "reduced" binding of altanserin particularly in the hippocampus in patients with major depressive disorder.cite journal
author = Mintun MA, Sheline YI, Moerlein SM, Vlassenko AG, Huang Y, Snyder AZ
title = Decreased hippocampal 5-HT2A receptor binding in major depressive disorder: in vivo measurement with [18F] altanserin positron emission tomography
journal = Biological Psychiatry
volume = 55
issue = 3
pages = 217–24
year = 2004
pmid = 14744461
doi = 10.1016/j.biopsych.2003.08.015] Another PET study reported "increased" altanserin binding in the caudate nuclei in obsessive compulsive disorder patients compared to a healthy control group.Cite journal
author = Adams KH, Hansen ES, Pinborg LH, Hasselbalch SG, Svarer C, Holm S, Bolwig TG, Knudsen GM
title = Patients with obsessive-compulsive disorder have increased 5-HT_2A receptor binding in the caudate nuclei
journal = International Journal of Neuropsychopharmacology
volume = 8
issue = 3
pages = 391–401
year = 2005
pmid = 15801987
doi = 10.1017/S1461145705005055]

Patients with Tourette's syndrome have also been scanned and the study found an increased binding of altanserin for patients compared to healthy controls.cite journal | author = Haugbøl S, Pinborg LH, Regeur L, Hansen ES, Bolwig TG, Nielsen FA, Svarer C, Skovgaard LT, Knudsen GM | title = Cerebral 5-HT2A receptor binding is increased in patients with Tourette's syndrome | journal = Int. J. Neuropsychopharmacol. | volume = 10 | issue = 2 | pages = 245–52 | year = 2007 | pmid = 16945163 | doi = 10.1017/S1461145706006559 | issn = ] The altanserin uptake decreases with age reflecting a loss of specific 5-HT_2A receptors with age.cite journal
author = Rosier A, Dupont P, Peuskens J, Bormans G, Vandenberghe R, Maes M, de Groot T, Schiepers C, Verbruggen A, Mortelmans L
title = Visualisation of loss of 5-HT_2A receptors with age in healthy volunteers using [18F] altanserin and positron emission tomographic imaging
journal = Psychiatry Res.
volume = 68
issue = 1
pages = 11–22
year = 1996
pmid = 9027929
doi = 10.1016/S0925-4927(96)02806-5] Cite journal
author = Meltzer CC, Smith G, Price JC, Reynolds CF, Mathis CA, Greer P, Lopresti B, Mintun MA, Pollock BG, Ben-Eliezer D, Cantwell MN, Kaye W, DeKosky ST
title = Reduced binding of [18F] altanserin to serotonin type 2A receptors in aging: persistence of effect after partial volume correction
journal = Brain Res.
volume = 813
issue = 1
pages = 167–171
year = 1998
pmid = 9824691
doi = 10.1016/S0006-8993(98)00909-3] Cite journal
author = Adams KH, Pinborg LH, Svarer C, Hasselbalch SG, Holm S, Haugbøl S, Madsen K, Frøkjaer V, Martiny L, Olaf B. Paulson, Knudsen GM
title = A database of [¹⁸F] -altanserin binding to 5-HT_2A receptors in normal volunteers: normative data and relationship to physiological and demographic variables
journal = NeuroImage
volume = 21
issue = 3
pages = 1105–1113
year = 2004
pmid = 15006678
doi = 10.1016/j.neuroimage.2003.10.046] A study has also found a positive correlation among healthy subjects between altanserin binding and the personality trait neuroticism as measure by the NEO PI-R personality questionnaire.Cite journal
author = Frøkjær VG, Mortensen EL, Nielsen FÅ, Haugbøl S, Pinborg LH, Adams KH, Svarer C, Hasselbalch SG, Holm S, Olaf B. Paulson, Knudsen GM
title = Frontolimbic serotonin 2A receptor binding in healthy subjects is associated with personality risk factors for affective disorder | journal = Biological Psychiatry
volume = 63
issue = 6
pages = 569–76
year = 2008
pmid = 17884017
doi = 10.1016/j.biopsych.2007.07.009]

In virus endocytosis

5-HT_2A is a necessary receptor for clathrin mediated endocytosis of the human polyoma virus called JC virus, the causative agent of progressive multifocal leukoencephalopathy (PML), that enters cells like oligodendrocytes, astrocytes, B lymphocytes, and kidney epithelial cells. These cells need to express both the alpha 2-6–linked sialic acid component of the 5HT_2A receptor in order to endocytose JCV.

References

External links

* [http://www.iuphar-db.org/GPCR/ReceptorDisplayForward?receptorID=2320 IUPHAR GPCR Database - 5-HT_2A]

*

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