Recombinant Mouse Taste receptor type 2 member 143 (Tas2r143)
Description
Introduction to Tas2r143
Tas2r143 is a mouse bitter taste receptor encoded by a gene located on chromosome 6. It belongs to the Class T2 (Taste 2) sensory receptors family, specifically the Taste 2 receptors subfamily . This receptor is also known by several alternative names including T2R143, Taste receptor type 2 member 43 (T2R43), and mT2R36 . Tas2r143 forms part of a gene cluster on mouse chromosome 6 that includes two other bitter taste receptor genes: Tas2r135 and Tas2r126 . This clustering arrangement suggests potential functional relationships or evolutionary connections between these receptors.
Bitter taste receptors like Tas2r143 evolved as detection mechanisms for potentially harmful substances in food, enabling animals to avoid toxic compounds. While traditionally associated with taste buds on the tongue, growing evidence indicates expression and functionality in extra-oral tissues, suggesting roles beyond taste perception . The ability to produce recombinant forms of Tas2r143 has significantly advanced our understanding of this receptor's structure, function, and potential applications in various research contexts.
Genetic Nomenclature and Identification
Tas2r143 has been assigned various synonyms and identifiers across different databases and literature sources:
Table 1: Tas2r143 Nomenclature and Database Identifiers
| Parameter | Identifier |
|---|---|
| Gene Symbol | Tas2r143 |
| Synonyms | Gm1404, mt2r36, Tas2r43, T2r36, T2R143, T2R43, mT2R36 |
| UniProt ID | Q7TQB9 |
| Accession Number | NM_001001452 |
| Organism | Mus musculus (Mouse) |
| Family | Class T2 (Taste 2) Sensory receptors Taste 2 receptors |
Expression Vectors and Tags
Recombinant Tas2r143 can be produced using various expression systems and vectors. Commercial suppliers offer Tas2r143 in different vector systems with various tags to facilitate purification and experimental applications. One common vector system is pCMV6-Entry, which allows for expression in mammalian cells with kanamycin resistance for selection in E. coli and neomycin resistance for mammalian cell selection .
Table 2: Expression Systems for Recombinant Tas2r143
| Expression System | Vector | Tags | Selection Marker | Application |
|---|---|---|---|---|
| Mammalian | pCMV6-Entry | Untagged | Kanamycin/Neomycin | Functional studies |
| Mammalian | pCMV6-Entry | tGFP-tagged | Kanamycin/Neomycin | Localization studies |
| Mammalian | pCMV6-Entry | Myc-DDK-tagged | Kanamycin/Neomycin | Immunodetection |
| E. coli | Not specified | His-tagged | Not specified | Protein purification |
Production and Purification
Recombinant mouse Tas2r143 protein can be produced in bacterial expression systems such as E. coli. The full-length protein (amino acids 1-293) fused to an N-terminal His-tag is available commercially . The purified protein is typically provided as a lyophilized powder with purity greater than 90% as determined by SDS-PAGE .
For storage and handling of recombinant Tas2r143 protein:
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Storage is recommended at -20°C/-80°C upon receipt
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Aliquoting is necessary for multiple use to avoid repeated freeze-thaw cycles
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The protein is typically stored in Tris/PBS-based buffer with 6% trehalose at pH 8.0
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Reconstitution in deionized sterile water to a concentration of 0.1-1.0 mg/mL is recommended
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Addition of 5-50% glycerol (final concentration) is suggested for long-term storage
Transmembrane Organization
As a member of the G protein-coupled receptor superfamily, Tas2r143 possesses a characteristic seven-transmembrane domain structure. These domains are interconnected by three extracellular loops (ECLs) and three intracellular loops (ICLs), with an extracellular N-terminus and an intracellular C-terminus .
The detailed structural organization of Tas2r143 includes:
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N-terminal domain (extracellular)
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Seven transmembrane domains (TM1-TM7)
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Three intracellular loops (ICL1-ICL3)
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Three extracellular loops (ECL1-ECL3)
The transmembrane domains are primarily composed of hydrophobic amino acids that span the cell membrane, while the loops contain more hydrophilic residues. This structural arrangement is critical for the receptor's function in signal transduction, where conformational changes triggered by ligand binding activate intracellular signaling pathways .
Functional Domains and Motifs
Analysis of the Tas2r143 sequence reveals several key functional domains and motifs typical of bitter taste receptors:
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Ligand-binding pocket: Primarily formed by the transmembrane domains and extracellular loops
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G protein coupling region: Located primarily in the intracellular loops, particularly ICL2 and ICL3
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Signal transduction elements: Various motifs throughout the sequence that facilitate conformational changes during activation
The detailed sequence information provided in the GPCRdb entry shows the specific amino acid composition of each structural element of the receptor, highlighting the complexity of this signaling protein .
Gustatory and Non-Gustatory Expression
To investigate the expression pattern of this bitter taste receptor cluster in non-gustatory tissues, researchers have developed a BAC (bacterial artificial chromosome) based transgenic mouse line expressing CreERT2 under the control of the Tas2r143 promoter. By crossing this line with a mouse line expressing EGFP after Cre-mediated recombination, researchers were able to monitor the expression of Tas2r143 in various tissues .
Expression Detection Methods
Several methodologies have been employed to detect and quantify Tas2r143 expression in different tissues:
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Transgenic Reporter Systems: BAC-based Tas2r143-CreERT2 transgenic mice crossed with Cre-reporter mice expressing fluorescent proteins
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Quantitative PCR: Real-time qPCR using Tas2r143-specific primers:
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Immunohistochemistry: Using antibodies against Tas2r143 or tagged versions of the receptor
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In situ hybridization: For detection of Tas2r143 mRNA in tissue sections
These methodologies have contributed to our expanding understanding of the physiological roles of bitter taste receptors beyond the gustatory system .
Ligand Binding and Signaling
Tas2r143, like other bitter taste receptors, functions by detecting specific bitter compounds and initiating intracellular signaling cascades. Upon ligand binding, these receptors activate G proteins, particularly gustducin (Gαgust), leading to the release of calcium from intracellular stores and subsequent cellular responses.
Functional studies of recombinant Tas2r143 typically involve:
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Heterologous expression in cell lines such as HEK293
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Calcium imaging to monitor receptor activation
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Ligand screening to identify specific bitter compounds recognized by Tas2r143
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Mutagenesis studies to identify critical residues for ligand binding and signal transduction
These studies provide insights into the specificity and sensitivity of Tas2r143 to various bitter compounds, contributing to our understanding of taste perception and potentially revealing novel applications in fields such as drug discovery and food science.
Research Applications
Recombinant Tas2r143 has numerous applications in research:
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Sensory Biology: Understanding the molecular basis of bitter taste perception in mice
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Comparative Biology: Comparing mouse Tas2r143 with human bitter taste receptors to elucidate evolutionary relationships
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Drug Discovery: Screening compounds for interaction with bitter taste receptors
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Physiological Studies: Investigating the role of Tas2r143 in non-gustatory tissues
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Transgenic Models: Using Tas2r143 promoter-driven expression systems to study gene function
The availability of recombinant Tas2r143 in various tagged forms facilitates diverse experimental approaches, from protein-protein interaction studies to subcellular localization analyses .
Transgenic Models
The development of transgenic mouse models has significantly advanced Tas2r143 research. A particularly valuable tool is the BAC-based Tas2r143-CreERT2 transgenic mouse line, which expresses the CreERT2 recombinase under the control of the Tas2r143 promoter. This model was generated using the BAC clone RP23-316O11 from mouse chromosome 6, which contains the Tas2r143, Tas2r135, and Tas2r126 genes .
When crossed with appropriate reporter mouse lines, these transgenic models allow for:
Product Specs
Please note: We prioritize shipping the format we have in stock. However, if you have specific format requirements, kindly indicate them in your order remarks, and we will prepare it accordingly.
All our proteins are shipped with standard blue ice packs by default. If you require dry ice shipping, please inform us in advance as additional fees will apply.
Generally, liquid form has a shelf life of 6 months at -20°C/-80°C. Lyophilized form has a shelf life of 12 months at -20°C/-80°C.
The tag type is determined during the production process. If you have a specific tag type requirement, please inform us, and we will prioritize its development.
Target Background
Q&A
What is Tas2r143 and where is it primarily expressed?
Tas2r143 is a G protein-coupled receptor belonging to the bitter taste receptor family (TAS2Rs) in mice. While traditionally associated with taste perception in the tongue, research has identified Tas2r143 expression in multiple extraoral tissues. Transcriptomic analyses have detected Tas2r143 in mouse airways, lungs, testicular Sertoli cells (specifically TM4 cells), and gingival fibroblasts (MGFs) . The receptor forms part of a gene cluster with Tas2r135 and Tas2r126 without any other genes between them in the mouse genome, making them valuable targets for simultaneous genetic manipulation studies .
How does Tas2r143 function in the bitter taste reception pathway?
Tas2r143 functions as a chemosensor that detects bitter compounds and initiates signaling cascades. Upon activation by bitter ligands like salicin, Tas2r143 couples with gustducin (a G protein) to trigger intracellular calcium mobilization. Specifically, Tas2r143 activation leads to the dissociation of gustducin's α subunit (encoded by Gnat3) from its βγ subunits, activating phospholipase C beta 2 (Plcb2), which subsequently triggers calcium release and activates the TRPM5 cation channel . This signaling cascade represents the canonical bitter taste transduction pathway and can be experimentally monitored through calcium flux measurements using fluorescent calcium indicators .
What are the known ligands/agonists for Tas2r143?
Current research has identified salicin as a specific agonist for Tas2r143. Studies utilizing heterologous expression systems with Tas2r143 and chimeric G protein Gα16gust44 in HEK293 cells have confirmed that salicin (typically used at 10 mM concentration in experimental settings) can directly activate this receptor, resulting in measurable calcium mobilization . The receptor's activation by salicin has been specifically linked to downstream effects in gingival fibroblasts, where it inhibits LPS-induced expression of chemokines including CXCL1, CXCL2, and CXCL5 .
What genetic models are available for studying Tas2r143 function?
Several genetic approaches have been developed to study Tas2r143 function:
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CRISPR/Cas9-generated knockout models: Researchers have successfully generated triple knockout mice (Tas2r TKO) with deletions of the Tas2r143/Tas2r135/Tas2r126 cluster using CRISPR/Cas9 gene-editing technology . This approach utilized specifically designed sgRNAs targeting each receptor.
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siRNA knockdown models: For in vitro studies, siRNA-mediated knockdown has been employed to reduce Tas2r143 expression in cell lines like TM4 cells .
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Gustducin knockout mice (Gnat3−/−): These mice serve as an indirect model for studying Tas2r143 function since gustducin is a critical downstream signaling component of this receptor .
The validation of these models typically employs genomic PCR, sequencing, qRT-PCR for mRNA expression, and functional assays such as tasting responses to bitter compounds .
What cell culture systems are appropriate for studying Tas2r143?
Multiple cell culture systems have been successfully employed for Tas2r143 research:
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Heterologous expression systems: HEK293 cells transfected with Tas2r143 and chimeric G protein Gα16gust44 constructs provide a reliable system for studying receptor activation through calcium mobilization assays .
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Mouse gingival fibroblasts (MGFs): These cells naturally express Tas2r143 and its downstream signaling components (Gnat3, Plcb2, and TrpM5), making them suitable for studying physiological responses to receptor activation .
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TM4 cells: This mouse Sertoli cell line expresses high levels of Tas2r143 and has been used to study the receptor's role in regulating tight junction proteins in the blood-testis barrier .
When establishing these systems, researchers should verify receptor expression through qRT-PCR and validate functional responses using specific agonists like salicin .
How can Tas2r143 activation be measured in experimental settings?
Several methodological approaches can measure Tas2r143 activation:
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Calcium flux assays: The most direct method involves loading cells with calcium indicators and measuring intracellular calcium mobilization following receptor activation with agonists like salicin. This approach is particularly effective in heterologous expression systems with chimeric G proteins that couple taste receptor activation to calcium signaling .
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Downstream signaling assessment: Measuring the activation of signaling molecules like NF-κB through western blotting or reporter assays can indirectly indicate Tas2r143 activation .
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Gene expression analysis: Quantifying changes in the expression of downstream genes regulated by Tas2r143 signaling, such as tight junction proteins (occludin, ZO-1) or inflammatory mediators (CXCL1, CXCL2, CXCL5), can serve as functional readouts of receptor activation .
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Physiological response measurements: In tissue-specific studies, functional assays such as measuring airway relaxation, periodontal bone loss, or inflammatory cell infiltration can assess the biological consequences of Tas2r143 activation or deletion .
What signaling pathways are activated downstream of Tas2r143?
Research has identified two primary signaling pathways downstream of Tas2r143:
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Canonical taste signaling pathway: In both oral and extraoral tissues, Tas2r143 activation couples to gustducin (specifically the α-subunit encoded by Gnat3), leading to activation of phospholipase C beta 2 (Plcb2) and subsequent calcium mobilization through TRPM5 channels . This pathway has been demonstrated in gingival fibroblasts, where it mediates anti-inflammatory effects.
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NF-κB signaling pathway: In Sertoli cells, Tas2r143 activation regulates the NF-κB pathway, which in turn modulates the expression of tight junction proteins, including occludin and ZO-1 . Knockdown of Tas2r143 significantly reduces NF-κB expression at both mRNA and protein levels, suggesting a direct regulatory relationship.
These pathways operate in a tissue-specific manner, potentially explaining the diverse physiological roles of Tas2r143 beyond taste perception.
How does Tas2r143 interact with other Tas2r family members?
Tas2r143 forms a gene cluster with Tas2r135 and Tas2r126 in the mouse genome without any other genes between them . This clustering suggests possible functional relationships, although current research has primarily focused on their collective deletion rather than specific interactions. In airway and lung tissues, Tas2r143 is co-expressed with several other Tas2r family members, including Tas2r108, 117, 119, 126, 135, 136, 137, and 138 in airways, and Tas2r126, 135, and 137 in lungs .
The functional significance of this co-expression remains unclear, especially given the surprising finding that bitter tastant-induced bronchodilation occurs independently of these receptors . This suggests potential redundancy within the Tas2r family or the existence of alternative mechanisms for bitter compound sensing in extraoral tissues.
What is the relationship between Tas2r143 and tight junction protein regulation?
In Sertoli cells, Tas2r143 plays a critical role in regulating blood-testis barrier integrity through modulation of tight junction proteins. Experimental knockdown of Tas2r143 using siRNA resulted in significant downregulation of occludin and ZO-1 expression at both mRNA and protein levels . This regulatory effect appears to be mediated through the NF-κB signaling pathway, as demonstrated by co-treatment experiments with Tas2r143 siRNA and NF-κB inhibitors.
The siRNA-133 (targeting Tas2r143) plus NF-κB inhibitor co-treatment group showed significantly greater downregulation of occludin and ZO-1 compared to either treatment alone, suggesting that Tas2r143 likely regulates tight junction protein expression primarily through the NF-κB signaling pathway . This mechanism has important implications for understanding how bitter taste receptors might contribute to maintaining the immune microenvironment in the testes and potentially other tissues with barrier functions.
What is the role of Tas2r143 in respiratory physiology?
These findings challenge the prevailing hypothesis about Tas2r-mediated bronchodilation and suggest that alternative mechanisms, possibly involving other receptors or direct effects on smooth muscle, may be responsible for the observed effects of bitter compounds on airways . This unexpected result highlights the importance of genetic validation in establishing the physiological roles of taste receptors in extraoral tissues.
How does Tas2r143 contribute to reproductive physiology?
Tas2r143 is highly expressed in mouse testicular Sertoli cells (TM4 cells) and appears to play a crucial role in maintaining the blood-testis barrier (BTB) integrity . The receptor regulates the expression of tight junction proteins occludin and ZO-1 through the NF-κB signaling pathway. When Tas2r143 is knocked down using siRNA, there is significant downregulation of these tight junction proteins, potentially compromising BTB function.
This regulatory mechanism suggests that Tas2r143 may serve as a chemosensor in the testes, potentially detecting harmful substances and initiating protective responses to maintain the immune microenvironment essential for proper spermatogenesis . This represents a novel function for bitter taste receptors in reproductive physiology and opens new avenues for understanding the chemical perception mechanisms involved in spermatogenesis.
What is the relationship between Tas2r143 activation and periodontal health?
Recent research has uncovered a protective role for Tas2r143 in periodontal health. Mouse gingival fibroblasts (MGFs) express Tas2r143 along with downstream signaling components (Gnat3, Plcb2, and TrpM5) . Activation of Tas2r143 by salicin inhibits LPS-induced expression of chemokines (CXCL1, CXCL2, and CXCL5) in these cells, suggesting an anti-inflammatory function.
In vivo experiments with periodontitis mouse models showed that salicin treatment inhibited periodontal bone loss, inflammatory/chemotactic factor expression, and neutrophil infiltration . Importantly, these protective effects were abolished in gustducin knockout (Gnat3−/−) mice, confirming the involvement of the taste signaling pathway. This suggests that Tas2r143 activation by bitter compounds like salicin may represent a promising approach for alleviating periodontal inflammation by stimulating the "solitary chemosensory cell-like" function of gingival fibroblasts .
How do we reconcile contradictory findings regarding Tas2r143 function across different tissues?
The literature reveals seemingly contradictory findings regarding Tas2r143 function, particularly between respiratory and other tissues. While genetic deletion studies indicate that Tas2r143 (along with Tas2r135 and Tas2r126) is not required for bitter tastant-induced bronchodilation , other studies demonstrate clear functional roles in testicular Sertoli cells and gingival fibroblasts .
These contradictions might be explained by:
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Tissue-specific signaling mechanisms: Tas2r143 may couple to different downstream effectors depending on the cellular context, leading to diverse physiological outcomes.
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Redundancy in bitter sensing mechanisms: In airways, alternative receptors or direct effects of bitter compounds on ion channels or other cellular components might compensate for Tas2r143 deletion.
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Differential expression of accessory proteins: The functional output of Tas2r143 might depend on the presence of specific scaffolding or regulatory proteins that vary across tissues.
To address these contradictions, future research should:
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Employ tissue-specific conditional knockout approaches
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Conduct comprehensive transcriptomic and proteomic analyses of Tas2r143-expressing tissues
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Investigate potential compensatory mechanisms following receptor deletion
What are the optimal experimental parameters for heterologous expression studies of Tas2r143?
For researchers establishing heterologous expression systems to study Tas2r143, several critical parameters should be considered:
When establishing this system, researchers should validate successful expression using RT-PCR and confirm functional coupling through calcium imaging experiments with known agonists before proceeding to experimental manipulations.
How can genetic compensation be addressed in Tas2r143 knockout studies?
The unexpected findings that Tas2r143/Tas2r135/Tas2r126 triple knockout mice still exhibit bitter tastant-induced bronchodilation highlight the challenge of genetic compensation in taste receptor research. To address this issue, researchers should consider:
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Comprehensive expression profiling: Perform RNA-seq analysis of tissues from wild-type and knockout mice to identify upregulated genes that might compensate for deleted receptors.
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Acute receptor inhibition: Compare chronic (genetic knockout) versus acute (pharmacological inhibition or inducible knockdown) receptor inactivation to distinguish between developmental compensation and functional redundancy.
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Combined approaches: Utilize both genetic deletions and dominant-negative constructs that might interfere with multiple family members.
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Cross-species validation: Compare findings across different species where the genetic architecture of Tas2r clusters may differ, potentially revealing conserved functional mechanisms.
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Proteomics approaches: Identify protein-protein interactions that might reveal functional complexes involving multiple taste receptors or alternative signaling components.
These strategies can help distinguish between true functional redundancy, compensatory upregulation, and the possibility that the observed physiological effects were incorrectly attributed to taste receptors in the first place.
