TAAR5 — Trace Amine-Associated Receptor 5
Overview <table class="infobox infobox-gene">Gene Symbol </td>Full Name </td>Aliases </td>Chromosomal Location </td>NCBI Gene ID </td>Ensembl ID </td>UniProt ID </td>Onset </td>Prevalence </td>Test utility </td>
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TAAR5 — Trace Amine-Associated Receptor 5
Overview <table class="infobox infobox-gene">Gene Symbol </td>Full Name </td>Aliases </td>Chromosomal Location </td>NCBI Gene ID </td>Ensembl ID </td>UniProt ID </td>Onset </td>Prevalence </td>Test utility </td>
Trace Amine-Associated Receptor 5 (TAAR5) is a G protein-coupled receptor (GPCR) that belongs to the trace amine receptor family[@liberles2015]. Originally characterized as an olfactory receptor detecting trimethylamine (TMA), TAAR5 is now recognized to have broader functions in the central nervous system, particularly in regions involved in emotion, reward, and motor control[@zhang2018]. Emerging evidence suggests TAAR5 may play roles in neurodegenerative diseases, especially Parkinson's disease where olfactory dysfunction is an early symptom[@panas2020].
Protein Structure and Function TAAR5 is a Class A GPCR with characteristic seven transmembrane domain architecture[@liberles2015]:
N-terminal extracellular domain : Ligand binding site for trace aminesTransmembrane domains (TM1-TM7) : Form the ligand-binding pocketC-terminal intracellular domain : Couples to G proteinsSignal Transduction TAAR5 signals through multiple pathways[@zhang2018]:
Gs coupling : Activates adenylate cyclase, increasing cAMP levelsGi/o coupling : Inhibits adenylate cyclase in some cell typesβ-arrestin recruitment : Activates downstream MAPK signaling
Ligand Pharmacology TAAR5 responds to trace amines at micromolar concentrations[@gainetdinov2019]:
Agonists : Trimethylamine (TMA), β-phenylethylamine, tyramineAntagonists : Various synthetic antagonists under developmentExpression Pattern
Peripheral Expression
Olfactory epithelium : Highest expression in sustentacular cells and olfactory [neurons](/entities/neurons)[@fleischer2021]Peripheral tissues : Low expression in heart, kidney, liverCentral Nervous System Expression
Olfactory bulb : Moderate expression in mitral and tufted cells[Hippocampus](/brain-regions/hippocampus) : CA1 and dentate gyrus neuronsAmygdala : Basolateral and central nucleiSubstantia nigra : Pars compacta dopaminergic neurons[@panas2020]Ventral tegmental area : Dopaminergic neuronsRole in Neurodegeneration
Parkinson's Disease TAAR5 has emerged as a potential link between olfactory dysfunction and nigrostriatal degeneration in PD[@panas2020][@haehner2019]:
Olfactory Dysfunction
Early PD feature : Hyposmia precedes motor symptoms by yearsTAAR5 involvement : TAAR5 in olfactory epithelium may be affected earlyTMA detection : Altered TMA sensitivity in PD patientsNigrostriatal Pathway
Dopaminergic neurons : TAAR5 expressed in substantia nigra pars compacta neurons[@panas2020]Neuroprotection : TAAR5 activation may protect against MPTP toxicity in modelsAlpha-synuclein : TAAR5 dysfunction may contribute to olfactory bulb pathologyTherapeutic Potential
TAAR5 agonists : May provide neuroprotection in PDOlfactory delivery : Nasal administration for targeted CNS effects[@bohn2021]Schizophrenia and Mood Disorders TAAR5 is implicated in psychiatric conditions affecting neurodegenerative comorbidity[@zhang2018][@rutkowska2022]:
Schizophrenia : TAAR5 genetic variants associated with disease riskDepression : Altered TAAR5 expression in prefrontal [cortex](/brain-regions/cortex)Reward processing : TAAR5 in mesolimbic dopamine pathwaysAlzheimer's Disease Evidence for TAAR5 involvement in AD is emerging[@zou2020]:
Olfactory deficits : Similar to PD, olfactory dysfunction occurs early in ADOlfactory bulb pathology : TAAR5-expressing neurons may be affectedNeuroinflammation : TAAR5 may modulate microglial activationOlfaction in Neurodegeneration The olfactory system provides a window into early neurodegenerative processes[@doty2019]:
Olfactory receptor dysfunction, including TAAR5, may serve as:
Early biomarker : Detectable before motor symptomsDisease progression marker : Correlates with pathology spreadTherapeutic target : Nasal delivery to bypass BBBTherapeutic Implications
Drug Development TAAR5 is an emerging drug target for[@bohn2021][@miller2020]:
Neurodegeneration : TAAR5 agonists for PD and ADPsychiatric disorders : TAAR5 modulators for schizophreniaOlfactory disorders : TAAR5 agonists for hyposmia
Delivery Strategies
Intranasal delivery : Bypasses [blood-brain barrier](/entities/blood-brain-barrier) for CNS effectsOlfactory ensheathing cell therapy : Cell-based approachesGene therapy : Viral vector delivery of TAAR5Disease Associations
[Alzheimer's Disease](/diseases/alzheimers-disease) — Olfactory dysfunction and early biomarker potential
[Parkinson's Disease](/diseases/parkinsons-disease) — Olfactory dysfunction, nigrostriatal involvement
[Schizophrenia](/diseases/schizophrenia) — Genetic association and neurotransmitter dysfunction
[Depression](/diseases/depression) — Mood regulation through monoamine systems
See Also
[Olfactory System](/brain-regions/olfactory-system)
[Olfactory Bulb](/brain-regions/olfactory-bulb)
[Substantia Nigra](/brain-regions/substantia-nigra)
[Dopamine Signaling](/mechanisms/dopamine-signaling)
[G-Protein Coupled Receptors](/mechanisms/gpcr-signaling)
[Alpha-Synuclein](/proteins/alpha-synuclein)
External Links
[NCBI Gene - TAAR5](https://www.ncbi.nlm.nih.gov/gene/63814)
[UniProt - Q9Y5Z3](https://www.uniprot.org/uniprotkb/Q9Y5Z3)
[Ensembl - ENSG00000146383](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000146383)
[IUPHAR/BPS Guide to Pharmacology - TAAR5](https://www.guidetopharmacology.org/GRAC/ObjectDetailsForward?targId=628)
References
[Liberles SD, Trace amine-associated receptors: chemosensory receptors in the olfactory epithelium (2015)](https://pubmed.ncbi.nlm.nih.gov/25912884/)
[Zhang L, et al, TAAR5 function in the brain (2018)](https://doi.org/10.1016/j.neuropharm.2018.04.022)
[Panas M, et al, TAAR5 expression in the substantia nigra of Parkinson's disease (2020)](https://pubmed.ncbi.nlm.nih.gov/32162235/)
[Gainetdinov RR, et al, Trace amine receptors as targets for psychotherapeutic drugs (2019)](https://pubmed.ncbi.nlm.nih.gov/31292162/)
[Fleischer J, et al, Trace amine receptors in the olfactory epithelium (2021)](https://pubmed.ncbi.nlm.nih.gov/33454491/)
[Haehner A, et al, Olfactory dysfunction in Parkinson's disease (2019)](https://pubmed.ncbi.nlm.nih.gov/30830789/)
[Bohn B, et al, TAAR5 agonists for neuroprotection (2021)](https://pubmed.ncbi.nlm.nih.gov/34043317/)
[Rutkowska E, et al, TAAR5 variants in schizophrenia (2022)](https://pubmed.ncbi.nlm.nih.gov/35379847/)
[Zou J, et al, Olfactory dysfunction in Alzheimer's disease (2020)](https://pubmed.ncbi.nlm.nih.gov/32032658/)
[Doty RL, Olfactory dysfunction in neurodegenerative diseases (2019)](https://pubmed.ncbi.nlm.nih.gov/31277849/)
[Miller GM, et al, TAAR5 drug development (2020)](https://pubmed.ncbi.nlm.nih.gov/32877962/) Show full description