Editing Cannabinoid receptor (section)

{{short description|Group of receptors to cannabinoid compounds}}
{{human-centric|date=May 2024}}
{{Infobox protein
| Name       = [[cannabinoid receptor 1]]
| image      = Human cannabinoid receptor 1 (CB1) PDB 5XRA.png
| width      = 120
| caption    = Human cannabinoid receptor 1 (CB<sub>1</sub>) bound to tetrahydrocannabinol agonist AM11542 (black). {{PDB|5XRA}}
| Symbol     = CNR1
| AltSymbols = CNR
| IUPHAR_id  = 
| EntrezGene = 1268
| HGNCid     = 2159
| OMIM       = 114610
| HomoloGene = 7273
| RefSeq     = NM_033181
| UniProt    = P21554
| ECnumber   = 
| Chromosome = 6
| Arm        = q
| Band       = 14
| LocusSupplementaryData = -q15
}}
{{Infobox protein
| Name       = [[cannabinoid receptor 2]]
| image      = Human cannabinoid receptor 2 (CB2) PDB 5ZTY.png
| width      = 120
| caption    = Human cannabinoid receptor 2 (CB<sub>2</sub>) bound to agonist AM10257 (black). {{PDB|5ZTY}}
| Symbol     = CNR2
| AltSymbols = 
| IUPHAR_id  = 
| EntrezGene = 1269
| HGNCid     = 2160
| OMIM       = 605051
| HomoloGene = 1389
| PDB        = 
| RefSeq     = NM_001841
| UniProt    = P34972
| ECnumber   = 
| Chromosome = 1
| Arm        = p
| Band       = 
| LocusSupplementaryData = 
}}
{{Cannabis sidebar}}
[[File:Cb1 cb2 structure.png|class=skin-invert-image|thumb|237px|[[Cannabinoid receptor 1|CB<sub>1</sub>]] and [[Cannabinoid receptor 2|CB<sub>2</sub>]] structures]]

'''Cannabinoid receptors''', located throughout the body, are part of the [[endocannabinoid system]] of vertebrates{{ndash}} a class of [[cell membrane]] [[Receptor (biochemistry)|receptor]]s in the [[G protein-coupled receptor]] superfamily.<ref name="pmid12432948"/><ref name="pmid18426493"/><ref name="pmid19273110"/><ref>{{cite journal | vauthors = Aizpurua-Olaizola O, Elezgarai I, Rico-Barrio I, Zarandona I, Etxebarria N, Usobiaga A | title = Targeting the endocannabinoid system: future therapeutic strategies | journal = Drug Discovery Today | volume = 22 | issue = 1 | pages = 105–110 | date = January 2017 | pmid = 27554802 | doi = 10.1016/j.drudis.2016.08.005 | s2cid = 3460960 | url = https://figshare.com/articles/journal_contribution/5028362 | access-date = 2022-10-19 | archive-date = 2023-01-27 | archive-url = https://web.archive.org/web/20230127151549/https://figshare.com/articles/journal_contribution/Targeting_the_endocannabinoid_system_future_therapeutic_strategies/5028362 | url-status = live }}</ref> As is typical of G protein-coupled receptors, the cannabinoid receptors contain seven transmembrane spanning domains.<ref name="pmid7556170"/> Cannabinoid receptors are activated by three major groups of [[ligand (biochemistry)|ligands]]: 

* [[Endocannabinoids]]; 
* [[Phytocannabinoid]]s (plant-derived such as [[tetrahydrocannabinol]] (THC) produced by [[cannabis]]); 
* [[Chemical synthesis|Synthetic]] cannabinoids (such as [[HU-210]]). 

All endocannabinoids and phytocannabinoids are [[lipophilic]].

There are two known subtypes of cannabinoid receptors, termed [[cannabinoid receptor type 1|CB<sub>1</sub>]] and [[cannabinoid receptor type 2|CB<sub>2</sub>]].<ref name="pmid2165569"/><ref name="pmid1718258"/> The CB<sub>1</sub> receptor is expressed mainly in the [[human brain|brain]] ([[central nervous system]] or "CNS"), but also in the [[lung]]s, [[liver]] and [[kidney]]s. The CB<sub>2</sub> receptor is expressed mainly in the [[immune system]], in [[Pluripotential hemopoietic stem cell|hematopoietic cells]],<ref name="pmid21295074">{{cite journal | vauthors = Pacher P, Mechoulam R | title = Is lipid signaling through cannabinoid 2 receptors part of a protective system? | journal = Progress in Lipid Research | volume = 50 | issue = 2 | pages = 193–211 | date = April 2011 | pmid = 21295074 | pmc = 3062638 | doi = 10.1016/j.plipres.2011.01.001 }}</ref> and in parts of the brain.<ref name="pmid30611802">{{cite journal | vauthors = Jordan CJ, Xi ZX | title = Progress in brain cannabinoid CB2 receptor research: From genes to behavior | journal = Neuroscience and Biobehavioral Reviews | volume = 98 | pages = 208–220 | date = March 2019 | pmid = 30611802 | doi = 10.1016/j.neubiorev.2018.12.026 | pmc = 6401261 }}</ref>

The protein sequences of CB<sub>1</sub> and CB<sub>2</sub> receptors are about 44% similar.<ref name=latek>{{cite journal | vauthors = Latek D, Kolinski M, Ghoshdastider U, Debinski A, Bombolewski R, Plazinska A, Jozwiak K, Filipek S | display-authors = 6 | title = Modeling of ligand binding to G protein coupled receptors: cannabinoid CB1, CB2 and adrenergic β 2 AR | journal = Journal of Molecular Modeling | volume = 17 | issue = 9 | pages = 2353–66 | date = September 2011 | pmid = 21365223 | doi = 10.1007/s00894-011-0986-7 | s2cid = 28365397 }}</ref><ref name="pmid7689702"/> When only the transmembrane regions of the receptors are considered, amino acid similarity between the two receptor subtypes is approximately 68%.<ref name="pmid7556170"/> In addition, minor variations in each receptor have been identified. Cannabinoids bind reversibly and [[stereochemistry|stereo-selectively]] to the cannabinoid receptors. Subtype selective cannabinoids have been developed which theoretically may have advantages for treatment of certain diseases such as obesity.<ref name="pmid17148745">{{cite journal | vauthors = Kyrou I, Valsamakis G, Tsigos C | title = The endocannabinoid system as a target for the treatment of visceral obesity and metabolic syndrome | journal = Annals of the New York Academy of Sciences | volume = 1083 | issue =  1| pages = 270–305 | date = November 2006 | pmid = 17148745 | doi = 10.1196/annals.1367.024 | bibcode = 2006NYASA1083..270K | s2cid = 23486551 }}</ref>

Enzymes involved in biosynthesis/inactivation of [[endocannabinoid]]s and endocannabinoid signaling in general (involving targets other than CB1/2-type receptors) occur throughout the animal kingdom.<ref>{{cite journal | vauthors = Elphick MR | title = The evolution and comparative neurobiology of endocannabinoid signalling | journal = Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences | volume = 367 | issue = 1607 | pages = 3201–15 | date = December 2012 | pmid = 23108540 | pmc = 3481536 | doi = 10.1098/rstb.2011.0394 }}</ref>