image of an orange circle Annotated and awaiting review. Please contact us if you can help with reviewing. 

TA1 receptor

Family: Trace amine receptor

Contents:
Gene and Protein Information
Previous and Unofficial Names
Database Links
Agonists
Antagonists
Allosteric Regulators
Transduction Mechanisms
Tissue Distribution
Expression Datasets
Functional Assays
Physiological Functions
Physiological Consequences of Altering Gene Expression
Phenotypes, Alleles and Disease Models
Biologically Significant Variants
General Comments
References
Gene and Protein Information
class A G protein-coupled receptor
Species TM AA Chromosomal Location Gene Symbol Gene Name Reference
Human 7 339 6q23.2 TAAR1 trace amine associated receptor 1 4,6
Mouse 7 332 10 A3 Taar1 trace amine-associated receptor 1 6
Rat 7 332 1p12 Taar1 trace-amine-associated receptor 1 4,27
Previous and Unofficial Names
TRAR1
TAAR1
TAR1
TAA1
TaR-1
BO111
TA1
trace amine receptor 1
trace amine associated receptor 1
trace amine-associated receptor 1
trace-amine-associated receptor 1
Database Links
ChEMBL Target
DrugBank Target
Ensembl
Entrez Gene
GeneCards
GenitoUrinary Development Molecular Anatomy Project
HomoloGene
Human Protein Reference Database
InterPro
KEGG Gene
OMIM
PharmGKB Gene
PhosphoSitePlus
Protein Ontology (PRO)
RefSeq Nucleotide
RefSeq Protein
TreeFam
UniGene Hs.
UniProt
Wikipedia
Search for 3D structures on the PDB
Search by keyword: Trace amine receptor TA1 receptor
Natural/Endogenous Ligand(s)
β-phenylethylamine
dopamine
octopamine
tyramine
Rank order of potency
Agonists
Key to terms and symbols View all chemical structures Click column headers to sort
Ligand Sp. Action Affinity Units Reference
[3H]tyramine Hs Full agonist 7.7 pKd 4
RO5166017 Mm Partial agonist 8.7 pKi 30
RO5166017 Rn Full agonist 8.6 pKi 30
RO5166017 Hs Full agonist 7.5 pKi 30
tyramine Rn Full agonist 7.2 pKi 5
tyramine Mm Agonist 6.4 pKi 5
RO5166017 Mm Partial agonist 8.5 pEC50 30
RO5166017 Rn Full agonist 7.9 pEC50 30
3-iodothyronamine Rn Full agonist 7.5 – 7.9 pEC50 13,32,38
dextroamphetamine Mm Full agonist 6.7 – 8.7 pEC50 27,41
RO5166017 Hs Full agonist 7.3 pEC50 30
tyramine Rn Full agonist 6.9 – 7.2 pEC50 5-6,27
β-phenylethylamine Mm Full agonist 6.3 – 7.4 pEC50 14,27,41
3-iodothyronamine Mm Full agonist 6.5 – 7.0 pEC50 13,32,38
tyramine Mm Full agonist 6.2 – 7.1 pEC50 5,14,27,41
β-phenylethylamine Hs Full agonist 6.2 – 7.0 pEC50 3-4,14-15,17,39
R(-)amphetamine Hs Full agonist 6.6 pEC50 3
R(-)amphetamine Rn Partial agonist 6.5 – 6.7 pEC50 6,27
β-phenylethylamine Rn Full agonist 6.4 – 6.6 pEC50 6,27
dextroamphetamine Hs Full agonist 6.0 – 6.9 pEC50 3,16
dextroamphetamine Rn Full agonist 6.1 – 6.4 pEC50 6,27
R(-)amphetamine Mm Full agonist 5.3 – 7.2 pEC50 27,41
tyramine Hs Full agonist 5.8 – 6.7 pEC50 3-5,14-15,39
R(-)amphetamine Hs Full agonist 6.2 pEC50 16
octopamine Rn Full agonist 5.9 pEC50 6
octopamine Mm Full agonist 5.4 – 5.8 pEC50 14,41
octopamine Hs Full agonist 4.8 – 5.8 pEC50 3-4,14-15,39
View species-specific agonist tables
Agonist Comments
There is a lack of specific agonists, which makes investigation of the TA1 receptor difficult outside of isolated expression systems. Species differences do exist, although a greater body of comparable literature is required to confirm these. Radiolabelled 3-iodothyronamine has been synthesised [23] but has not been fully characterised and is not yet commercially available.

There are two reports of selective TA1 partial agonists. (1) RO5203648. In HEK293 cells, Ki values were 6.8nM (human TA1), 1nM (rat TA1) and 0.5nM (mouse TA1). EC50 (and Emax compared to β-Phenylethylamine) values in cAMP assay were 30nM (73%) for human, 6.8nM (59%) for rat and 4nM (48%) for mouse TA1 [31]. (2) RO5073012. Ki human TA1 6nM with 140 fold selectivity for TA1 over adrenergic α2. In functional assay EC50 (Emax) values were 23nM (35%) for human TA1, 25nM (24%) for rat TA1 and 23nM (26%) for mouse TA1 [12].
Antagonists
Key to terms and symbols View all chemical structures Click column headers to sort
Ligand Sp. Action Affinity Units Reference
EPPTB Mm Inverse agonist 9.0 pKi 5,36
EPPTB Rn Inverse agonist 6.0 pKi 5
EPPTB Mm Inverse agonist 7.7 pIC50 5
EPPTB Rn Inverse agonist 5.4 pIC50 5
EPPTB Hs Inverse agonist 5.1 pIC50 5
View species-specific antagonist tables
Antagonist Comments
There are currently no commercially available antagonists available for the TA1 receptor, although lead compounds have been rationally synthesised but not yet fully characterised [37].

EPPTB (RO5212773) inhibited basal cAMP levels in HEK293 cells expressing human, rat and mouse TA1 receptors and has 1000 fold selectivity for the mouse TA1 receptor. In Schild analysis RO5212773 was a competitive antagonist [5].
Allosteric Regulator Comments
There are currently no known allosteric regulators of the TA1 receptor.

Explore drug-target interactions for this set of compounds using iPHACE

Primary Transduction Mechanisms
Transducer Effector/Response
Gs family Adenylate cyclase stimulation
Comments:  Tyramine causes an increase in intracellular cAMP in HEK293 or COS-7 cells expressing the TA1 receptor in vitro [4,6,18]. In addition, coupling to a promiscuous Gαq has been observed, resulting in increased intracellular calcium concentration [24]. In vivo transduction mechanisms have not yet been studied. In HEK293 cells expressing human, rat or mouse TA1 the receptor is reported to exhibit constitutive active as basal levels of cAMP were reduced by the TA1 selective compound RO5212773 (EPPTB) [5].
References:  4,6,18
Secondary Transduction Mechanisms
Transducer Effector/Response
Gq/G11 family
Comments:  RD-HGA16 cells express the promiscuous Gq protein Gα16 that allows the coupling of TA1 to the mobilisation of intracellular calcium [16-17].
References: 
Tissue Distribution
Primary Tonsillar B Cells
Species:  Human
Technique:  Western blot
References:  9
Pancreatic islet β cells.
Species:  Human
Technique:  In situ hybridisation, RT-PCR
References:  28
Circulating leukocytes of healthy subjects (upregulation occurs upon addition of phytohaemagglutinin).
Species:  Human
Technique:  RT-PCR
References:  8,25
Malignancy-derived B Cells
Species:  Human
Technique:  Western blot
References:  40
Leukocytes
Species:  Human
Technique:  RT-PCR
References:  2
CNS (region specific) & several peripheral tissues:
Stomach > amygdala, kidney, lung, small intestine > cerebellum, dorsal root ganglion, hippocampus, hypothalamus, liver, medulla oblongata, pancreas, pituitary gland, pontine reticular formation, prostate, skeletal muscle, spleen.
Species:  Human
Technique:  RT-PCR
References:  4
CNS:
Mitral cell layer of olfactory bulb, piriform cortex, arcuate, motor and mesencephalic trigeminal nuclei, lateral reticular and hypoglossal nuclei, cerebellar Purkinje cells, ventral horn of spinal cord > frontal, entorhinal and agranular cortices, ventral pallidum, thalamus, hypothalamic nuclei, hippocampus, ambiguus, dorsal raphe and gigantocellular reticular nuclei > septum, basal ganglia, amygdala, myelencephalon, dorsal horn of the spinal cord.
Species:  Mouse
Technique:  in situ hybridisation
References:  4
Substantia nigra (dopaminergic neurons).
Species:  Mouse
Technique:  Immunohistochemistry
References:  44
Brain regions associated with corticolimbic dopaminergic systems: substantia nigra/ventral tegmental area, nucleus accumbens, frontal cortex.
Species:  Mouse
Technique:  RT-PCR
References:  9
Aorta
Species:  Rat
Technique:  RT-PCR, Western blot
References:  11
Cardiac ventricles.
Species:  Rat
Technique:  RT-PCR
References:  7
Tissue Distribution Comments
In the brain (mouse, rhesus monkey) the TA1 receptor localises to neurones within the momaminergic pathways and there is emerging evidence for a modulatory role for TA1 on function of these systems. Co-expression of TA1 with the dopamine transporter (either within the same neurone or in adjacent neurones) implies direct/indirect modulation of CNS dopaminergic function. In cells expressing both human TA1 and a monoamine transport (DAT, SERT or NET) signalling via TA1 is enhanced [22,42-44].
Expression Datasets

Click here to show/hide data

Log average relative transcript abundance in mouse tissues measured by qPCR from Regard, J.B., Sato, I.T., and Coughlin, S.R. (2008). Anatomical profiling of G protein-coupled receptor expression. Cell, 135(3): 561-71. [PMID:18984166] [Raw data: website]

There should be a chart of expression data here, you may need to enable JavaScript!
Functional Assays
Measurement of cAMP levels in COS-7 cells transfected with the human TA1 receptor.
Species:  Human
Tissue:  COS-7 cells.
Response measured:  Intracellular cAMP accumulation.
References:  4
Measurement of the inward chloride current in Xenopus oocytes co-transfected with human TA1 and CFTR in response to tyramine.
Species:  Human
Tissue:  Xenopus laevis oocytes
Response measured:  Inward chloride current
References:  4
Measurement of cAMP levels in HEK293 cells transfected with the human TA1 receptor.
Species:  Human
Tissue:  HEK293 cells.
Response measured:  Intracellular cAMP accumulation.
References:  18
Fluorometry of intracellular calcium concentration in Chinese Hamster Ovary (CHO) cells expressing the promiscuous Gq, Gα16 and human TA1 receptor.
Species:  Human
Tissue:  CHO cells
Response measured:  Increase in cytopasmic calcium
References:  24
Measurement of cAMP levels in HEK293 cells transfected with the murine TA1 receptor.
Species:  Mouse
Tissue:  HEK293 cells.
Response measured:  Intracellular cAMP accumulation.
References:  38,41
Activation of leukocytes
Species:  Human
Tissue:  PMN, T and B cells
Response measured:  Chemotactic migration towards TA1 ligands (β-Phenylethylamine, tyramine and 3-iodothyronamine), trace amine induced IL-4 secretion (T-cells) and trace amine induced regulation of T cell marker RNA expression, trace amine induced IgE secretion in B cells.
References:  2
β-Lactamase reporter assay
Species:  Human
Tissue:  HEK293/Cre-bla cells
Response measured:  Elevated β-lactamase activity
References:  14
Measurement of cAMP levels in HEK293 cells transfected with the rat TA1 receptor.
Species:  Rat
Tissue:  HEK293 cells
Response measured:  Intracellular cAMP accumulation
References:  38
Mobilization of internal calcium in RD-HGA16cells transfected with unmodified human TA1
Species:  Human
Tissue:  RD-HGA16 cells
Response measured:  Mobilization of intracellular calcium
References:  16-17
Inhibition of firing frequency of dopamine neurones in slice preparation of mouse brain ventral tegmental area.
Species:  Mouse
Tissue:  Midbrain slice
Response measured:  Inhibition of spontaneous dopamine neurone firing frequency
References:  5
β-Lactamase reporter assay
Species:  Mouse
Tissue:  HEK293/Cre-bla cells
Response measured:  Elevated β-lactamase activity
References:  14
Functional Assay Comments
Expression systems have proved effective in establishing assays for TA1 activity without the need for specific agonists and antagonists.
Physiological Functions
β-PEA inhibited uptake and induced efflux of [3H]dopamine and [3H]serotonin in striatal and [3H]norepinephrine in thalamic synaptosomes of wild-type mice and in HEK293 cells expressing TA1.
Species:  Mouse
Tissue:  Striatal and thalamic synaptosomes.
References:  42-43
Inhibition of firing frequency of dopminergic neurones
Species:  Mouse
Tissue:  Brain
References:  5,19,30-31
Physiological Consequences of Altering Gene Expression
Mice deficient in the TA1 receptor possess a phenotype with minor spontaneous hyperactivity, reduced prepulse inhibition, increased sensitisation to the psychomotor-stimulating effects of amphetamine, raised levels of dopamine and noradrenaline in the dorsal striatum, increased striatal D2 receptor expression and an elevated spontaneous firing rate of dopaminergic neurons in the ventral tegmental area compared with the wild type. This has been proposed as an animal model of schizophrenia and also as hemi-parkinsonian.
Species:  Mouse
Tissue: 
Technique:  Gene targeting in embryonic stem cells
References:  19,35,41
β-PEA inhibited uptake and induced efflux of [3H]dopamine and [3H]serotonin in striatal and [3H]norepinephrine in thalamic synaptosomes of wild-type but not TA1 knockout mice.
Species:  Mouse
Tissue: 
Technique:  Gene targeting in embryonic stem cells.
References:  42-43
Knockout animals exhibit a significant augmentation of methamphetamine induced locomotor activity and conditioned placement preference.
Species:  Mouse
Tissue:  in vivo whole animal
Technique:  Targeting in embryonic stem cells
References:  1
Functional interaction between TA1 and Dopamine D2 receptor. In TA1 knockout mouse haloperidol -induced striatal c-Fos expression and catalepsy are reduced.
Species:  Mouse
Tissue:  in vivo whole animal
Technique:  Targeting in embryonic stem cells
References:  10
Auto-inhibition of MDMA (Ecstasy) responses by TA1 receptor. Knockout animals indicate a role for TA1 in MDMA mediated hypothermia and in auto-inhibition of MDMA responses including release of dopamine and 5-HT in dorsal striatum and nucleus accumbens, locomotor activity, striatal tyrosine hydrolxylase phsophorylation.
Species:  Mouse
Tissue:  in vivo whole animal
Technique:  Targeting in embryonic stem cells
References:  9
Brain-specific overexpression of TA1 alters monoaminergic neurotransmission and decreased sensitivty to amphetamine. Increased spontaneous firing activity of monaminergic neurones in ventral tegmental area, dorsal raphe nucleus and locus coeruleus resulting from reduced GABAergic inhibitory input. Elevated basal release of monoamines. Hyposensitivity to locomotor effects of amphetamine that could be reversed with the TA1 partial agonist RO5073012.
Species:  Mouse
Tissue:  in vivo whole animal
Technique:  Gene over expression
References:  29
Phenotypes, Alleles and Disease Models Mouse data from MGI

Click here to show/hide data

Allele Composition & genetic background Accession Phenotype Id Phenotype Reference
Taar1tm1Tdw Taar1tm1Tdw/Taar1tm1Tdw
involves: 129S1/Sv * C57BL/6J
MGI:2148258  MP:0003964 abnormal noradrenaline level PMID: 17212650 
Taar1tm1Tdw Taar1tm1Tdw/Taar1tm1Tdw
involves: 129S1/Sv * C57BL/6J
MGI:2148258  MP:0003088 abnormal prepulse inhibition PMID: 17212650 
Taar1tm1Tdw Taar1tm1Tdw/Taar1tm1Tdw
involves: 129S1/Sv * C57BL/6J
MGI:2148258  MP:0009749 enhanced behavioral response to addictive substance PMID: 17212650 
Taar1tm1Tdw Taar1tm1Tdw/Taar1tm1Tdw
involves: 129S1/Sv * C57BL/6J
MGI:2148258  MP:0001906 increased dopamine level PMID: 17212650 
Taar1tm1Tdw Taar1tm1Tdw/Taar1tm1Tdw
involves: 129S1/Sv * C57BL/6J
MGI:2148258  MP:0008873 increased physiological sensitivity to xenobiotic PMID: 17212650 
Biologically Significant Variant Comments
A SNP (rs8192619) in the TA1 receptor was reported in a large candidate gene association study investigating genetic risk factors that may contribute to the aetiology of fibromyalgia [33].
General Comments
For comprehensive reviews of the TA1 receptor see: [20-21,26,34,45].

REFERENCES

To cite this database page, please use the following:

Janet J. Maguire, Anthony P. Davenport.
Trace amine receptor: TA1 receptor. Last modified on 15/03/2013. Accessed on 21/05/2013. IUPHAR database (IUPHAR-DB), http://www.iuphar-db.org/DATABASE/ObjectDisplayForward?objectId=364.


Contact us | Print | Back to top | Help