GPCR word cloud

What is MeSH?

The Medical Subject Headings (MeSH) thesaurus produced by the National Library of Medicine is a hierarchically organized vocabulary used to index, catalog, and search biomedical and health-related information in MEDLINE/PubMed. MeSH headings form a tree structure with many branches, and each branch has many levels of sub-branches. One can search PubMed efficiently by using appropriate MeSH terms instead of randomly trying one set of keywords after another or desperately peppering search terms with wildcards. Excellent tutorials are found here.


Some MeSH terms appear in multiple branches for good reasons. For instance, a heading Receptors, neuropeptide is mapped under Receptors, neurotransmitter and Receptors, peptide at the same time since both are reasonable generalizations of its characteristics. However, that classification strategy sometimes creates a mess and trap PubMed users. To give an example, let's look at purinergic receptors. Purinergic P2Y receptors are a subgroup of G protein-coupled receptors (GPCRs). There are also purinergic ion channels called P2X receptors. Understandably, these structurally unlike but functionally close groups of proteins are aggregated into Receptors, purinergic, but who can imagine that that Receptors, purinergic occupies a position in the Receptors, G-Protein-Coupled domain and contaminates it with ion channels! It is like classifying dolphins into fish because fish are finned creatures and dolphins have fins, too.

Another source of confusion is that the MeSH tree for GPCRs is somewhat busy, with a maximum of five branches from the GPCR kingdom at the top to the narrowest concept. Moreover, the ranks of MeSH headings are arbitrary and do not necessarily indicate their granularity; for instance, while PAR-2 receptor and β1-adrenoceptor are individual proteins, the former is in the second rank, and the latter in the fifth. Similarly, the tip of a branch can be a group, a subgroup, a protein, or something in between. This complexity contrasts with the simple taxonomy developed by Guide to Pharmacology (G2P), which consists of only three layers, the GPCR kingdom—receptor families—individual receptors, and looks more familiar to biologists.


To help search PubMed effectively, We have aligned the MeSH thesaurus for GPCRs with G2P's taxonomy (Table below). Indention indicates branching from higher-order headings. The terms in same row are meant to be the closest concepts, if not identical, from MeSH and G2P. Interestingly, Proto-Oncogene Mas, or MAS1, belongs to different groups, i.e., angiotensin receptors and class A orphans. That may serve as another pitfall if one takes either classification for granted while unaware of the other.

Table. GPCR MeSH headings aligned with G2P taxonomy

MeSH TreeGuide to Pharmacology. Family & Receptor NamesComment
Receptors, G-Protein-CoupledG protein-coupled receptors
Apelin ReceptorsApelin receptor
Calcitonin receptors
Calcitonin Receptor-Like Proteincalcitonin receptor-like receptor
Frizzled ReceptorsClass Frizzled GPCRs
Smoothened ReceptorSMO
Glucagon-Like Peptide ReceptorsGlucagon receptor family
Glucagon-Like Peptide-1 ReceptorGLP-1 receptor
Glucagon-Like Peptide-2 ReceptorGLP-2 receptor
Orexin ReceptorsOrexin receptors
Complement peptide receptors
Receptor, Anaphylatoxin C5aC5a1 receptor; C5a2 receptor
Proteinase-activated receptors
Receptor, PAR-2PAR2
Calcitonin receptors
Receptors, AdrenomedullinAM1 receptor; AM2 receptor
Receptors, AngiotensinAngiotensin receptors
Receptor, Angiotensin, Type 1AT1 receptor
Receptor, Angiotensin, Type 2AT2 receptor
Class A Orphans
Proto-Oncogene MasMAS1
Receptors, BombesinBombesin receptors
Receptors, BradykininBradykinin receptors
Receptor, Bradykinin B1B1 receptor
Receptor, Bradykinin B2B2 receptor
Calcitonin receptors
Receptors, CalcitoninCT receptor
Receptors, Calcitonin Gene-Related PeptideCGRP receptor
Receptors, Calcium-SensingCalcium-sensing receptor
CaS receptor
Receptors, CannabinoidCannabinoid receptors
Receptor, Cannabinoid, CB1CB1 receptor
Receptor, Cannabinoid, CB2CB2 receptor
Receptors, Catecholamine
Receptors, AdrenergicAdrenoceptors
Receptors, Adrenergic, alpha
Receptors, Adrenergic, alpha-1α 1A-adrenoceptor; α 1B-adrenoceptor; α 1D-adrenoceptor
Receptors, Adrenergic, alpha-2α 2A-adrenoceptor; α 2B-adrenoceptor; α 2C-adrenoceptor
Receptors, Adrenergic, beta
Receptors, Adrenergic, beta-1β 1-adrenoceptor
Receptors, Adrenergic, beta-2β 2-adrenoceptor
Receptors, Adrenergic, beta-3β 3-adrenoceptor
Receptors, DopamineDopamine receptors
Receptors, Dopamine D1D1 receptor
Receptors, Dopamine D5D5 receptor
Receptors, Dopamine D2D2 receptor
Receptors, Dopamine D3D3 receptor
Receptors, Dopamine D4D4 receptor
Receptors, ChemokineChemokine receptors
Receptors, CCR
Receptors, CCR1CCR1
Receptors, CCR10CCR10
Receptors, CCR2CCR2
Receptors, CCR3CCR3
Receptors, CCR4CCR4
Receptors, CCR5CCR5
Receptors, CCR6CCR6
Receptors, CCR7CCR7
Receptors, CCR8CCR8
Receptors, CXCR
CX3C Chemokine Receptor 1CX3CR1
Receptors, CXCR3CXCR3
Receptors, CXCR4CXCR4
Receptors, CXCR5CXCR5
Receptors, CXCR6CXCR6
Receptors, Interleukin-8
Receptors, Interleukin-8ACXCR1
Receptors, Interleukin-8BCXCR2
Receptors, CholecystokininCholecystokinin receptors
Receptor, Cholecystokinin ACCK1 receptor
Receptor, Cholecystokinin BCCK2 receptor
Receptors, Corticotropin-Releasing HormoneCorticotropin-releasing factor receptors
Receptors, Eicosanoid
Receptors, LeukotrieneLeukotriene receptors
Receptors, Leukotriene B4BLT1 receptor
Formylpeptide receptors
Receptors, LipoxinFPR2/ALX
Receptors, Prostaglandin
Prostanoid receptors
Receptors, EpoprostenolIP receptor
Receptors, Prostaglandin E
Receptors, Prostaglandin E, EP1 SubtypeEP1 receptor
Receptors, Prostaglandin E, EP2 SubtypeEP2 receptor
Receptors, Prostaglandin E, EP3 SubtypeEP3 receptor
Receptors, Prostaglandin E, EP4 SubtypeEP4 receptor
Receptors, Thromboxane A2, Prostaglandin H2TP receptor
Receptors, Thromboxane
Receptors, Thromboxane A2, Prostaglandin H2TP receptor
Receptors, EndothelinEndothelin receptors
Receptor, Endothelin AETA receptor
Receptor, Endothelin BETB receptor
Receptor, Endothelin BETB receptor
Receptor, Endothelin BETB receptor
Receptor, Endothelin BETB receptor
Receptors, Formyl PeptideFormylpeptide receptors
Glycoprotein hormone receptors
Receptors, FSHFSH receptor
Receptors, GABA-BGABAB receptors
Receptors, GalaninGalanin receptors
Receptor, Galanin, Type 1GAL1 receptor
Receptor, Galanin, Type 2GAL2 receptor
Receptor, Galanin, Type 3GAL3 receptor
Receptors, GhrelinGhrelin receptor
Receptors, GlucagonGlucagon receptor family
Histamine receptors
Receptors, Histamine H1H1 receptor
Receptors, Histamine H2H2 receptor
Receptors, Histamine H4H4 receptor
Calcitonin receptors
Receptors, Islet Amyloid PolypeptideAMY1 receptor; AMY2 receptor; AMY3 receptor
Receptors, Kisspeptin-1Kisspeptin receptor
Glycoprotein hormone receptors
Receptors, LHLH receptor
Gonadotrophin-releasing hormone receptors
Receptors, LHRHGnRH1 receptor
Receptors, Lysophospholipid
Receptors, Lysophosphatidic AcidLysophospholipid (LPA) receptors
Receptors, Lysosphingolipid
Sphingosine-1-Phosphate ReceptorsLysophospholipid (S1P) receptors
Sphingosine Phosphorylcholine ReceptorsLysophospholipid (S1P) receptors
Receptors, MelanocortinMelanocortin receptors
Receptor, Melanocortin, Type 1MC1 receptor
Receptor, Melanocortin, Type 2MC2 receptor
Receptor, Melanocortin, Type 3MC3 receptor
Receptor, Melanocortin, Type 4MC4 receptor
Receptors, MelatoninMelatonin receptors
Receptor, Melatonin, MT1MT1 receptor
Receptor, Melatonin, MT2MT2 receptor
Receptors, Metabotropic GlutamateMetabotropic glutamate receptors
Receptor, Metabotropic Glutamate 5mGlu5 recepto
Receptors, MuscarinicAcetylcholine receptors (muscarinic)
Receptor, Muscarinic M1M1 receptor
Receptor, Muscarinic M2M2 receptor
Receptor, Muscarinic M3M3 receptor
Receptor, Muscarinic M4M4 receptor
Receptor, Muscarinic M5M5 receptor
Receptors, Neuropeptide YNeuropeptide Y receptors
Receptors, NeurotensinNeurotensin receptors
Receptors, Odorant
Receptors, OpioidOpioid receptors
Receptors, Opioid, deltaδ receptor
Receptors, Opioid, kappaκ receptor
Receptors, Opioid, muμ receptor
Other protein targetsnot GPCRs
Receptors, sigmaSigma receptorsnot GPCRs
G protein-coupled receptors
Vasopressin and oxytocin receptors
Receptors, OxytocinOT receptor
Parathyroid hormone receptors
Receptors, Parathyroid Hormone
Receptor, Parathyroid Hormone, Type 1PTH1 receptor
Receptor, Parathyroid Hormone, Type 2PTH2 receptor
Receptors, PheromoneTrace amine receptor
Receptors, Mating Factorfungal
Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide
VIP and PACAP receptors
Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type IPAC1 receptor
Receptors, Vasoactive Intestinal Peptide
Receptors, Vasoactive Intestinal Peptide, Type IIVPAC2 receptor
Receptors, Vasoactive Intestinal Polypeptide, Type IVPAC1 receptor
Receptors, Purinergic
Receptors, Cyclic AMPbacterial
Adenosine receptors
Receptors, Purinergic P1
Receptor, Adenosine A1A1 receptor
Receptor, Adenosine A3A3 receptor
Receptors, Adenosine A2
Receptor, Adenosine A2AA2A receptor
Receptor, Adenosine A2BA2B receptor
Receptors, Purinergic P2
Ligand-gated ion channelsnot GPCRs
Receptors, Purinergic P2XP2X receptorsnot GPCRs
Receptors, Purinergic P2X1P2X1not a GPCR
Receptors, Purinergic P2X2P2X2not a GPCR
Receptors, Purinergic P2X3P2X3not a GPCR
Receptors, Purinergic P2X4P2X4not a GPCR
Receptors, Purinergic P2X5P2X5not a GPCR
Receptors, Purinergic P2X7P2X7not a GPCR
G protein-coupled receptors
Receptors, Purinergic P2YP2Y receptors
Receptors, Purinergic P2Y1P2Y1 receptor
Receptors, Purinergic P2Y12P2Y12 receptor
Receptors, Purinergic P2Y2P2Y2 receptor
Receptors, Serotonin5-Hydroxytryptamine receptors
Receptors, Serotonin, 5-HT1
Receptor, Serotonin, 5-HT1A5-HT1A receptor
Receptor, Serotonin, 5-HT1B5-HT1B receptor
Receptor, Serotonin, 5-HT1D5-HT1D receptor
Receptors, Serotonin, 5-HT2
Receptor, Serotonin, 5-HT2A5-HT2A receptor
Receptor, Serotonin, 5-HT2B5-HT2B receptor
Receptor, Serotonin, 5-HT2C5-HT2C receptor
Receptors, Serotonin, 5-HT45-HT4 receptor
Receptors, SomatostatinSomatostatin receptors
Receptors, TachykininTachykinin receptors
Receptors, Neurokinin-1NK1 receptor
Receptors, Neurokinin-2NK2 receptor
Receptors, Neurokinin-3NK3 receptor
Receptors, ThrombinProteinase-activated receptors
Receptor, PAR-1PAR1
Vasopressin and oxytocin receptors
Receptors, VasopressinV1A receptor; V1B receptor; V2 receptor
Opsin receptors
Transporters > SLC superfamily of solute carriers >not GPCRs
SLC53 Phosphate carriersnot GPCRs
Xenotropic and Polytropic Retrovirus Receptorxenotropic and polytropic retrovirus receptor 1not a GPCR

MeSH headings and Guide to Pharmacology taxonomy were retrieved on December 2, 2021, and November 21, 2021, respectively.

NB the table may not be displayed correctly on a tablet or a smartphone.