TAS2R1

Taste receptor type 2 member 1 (TAS2R1/T2R1) is a protein that in humans is encoded by the TAS2R1 gene.^[5][6][7] It belongs to the G protein-coupled receptor (GPCR) family and is related to class A-like GPCRs, they contain 7 transmembrane helix bundles and short N-terminus loop.^[8] Furthermore, TAS2R1 is member of the 25 known human bitter taste receptors, which enable the perception of bitter taste in the mouth cavity. Increasing evidence indicates a functional role of TAS2Rs in extra-oral tissues.^[9]

TAS2R1
Identifiers
Aliases	TAS2R1, T2R1, TRB7, taste 2 receptor member 1
External IDs	OMIM: 604796; MGI: 2681253; HomoloGene: 10480; GeneCards: TAS2R1; OMA:TAS2R1 - orthologs
Gene location (Human) Chr. Chromosome 5 (human)[1] Band 5p15.31 Start 9,627,347 bp[1] End 9,712,378 bp[1]
Gene location (Mouse) Chr. Chromosome 15 (mouse)[2] Band 15|15 B3.1 Start 32,177,435 bp[2] End 32,178,440 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in right testis left testis stromal cell of endometrium epithelium of colon placenta caudate nucleus putamen nucleus accumbens hippocampal formation prefrontal cortex Top expressed in proximal tubule right kidney genital tubercle More reference expression data BioGPS More reference expression data
Gene ontology Molecular function G protein-coupled receptor activity signal transducer activity taste receptor activity bitter taste receptor activity Cellular component plasma membrane membrane integral component of membrane Biological process G protein-coupled receptor signaling pathway detection of chemical stimulus involved in sensory perception of bitter taste signal transduction response to stimulus sensory perception of taste Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 50834 57254 Ensembl ENSG00000169777 ENSMUSG00000045267 UniProt Q9NYW7 Q9JKT2 RefSeq (mRNA) NM_019599 NM_001386348 NM_020503 RefSeq (protein) NP_062545 NP_065249 Location (UCSC) Chr 5: 9.63 – 9.71 Mb Chr 15: 32.18 – 32.18 Mb PubMed search [3] [4]
Wikidata
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Expression and function

Extra-oral roles of TAS2Rs

Bitter taste receptors are expressed in taste receptor cells, which organized into taste buds on the papillae of the tongue and palate epithelium.

In addition, TAS2Rs were found to be expressed in extra-oral tissues, e.g. brain, lungs, gastrointestinal tract, etc.^[9] So far, less is known about their function however, for example it was shown that:

• TAS2Rs mediate relaxation of airway smooth muscles.^[10]
• TAS2R43 is involved in secretion of gastric acid in the stomach.^[11]

Extra-oral roles of TAS2R1

• TAS2R1, TAS2R4, TAS2R10, TAS2R38 and TAS2R49 were found to be down-regulated in breast cancer cells^[12].
• TAS2R1, causes vasoconstrictor responses in the pulmonary circuit and relaxation in the airways^[13].

Structure of TAS2R1 receptor

Based on a recent homology model from BitterDB^[14][15] several conserved motifs, which are counterparts to Class A GPCRs^[8] were found:

• Transmembrane helix 1: N^1.50xxI^1.53
• Transmembrane helix 2: L^2.46xxxR^2.50
• Transmembrane helix 3: F^3.49Y^3.50xxK^3.53
• Transmembrane helix 5: P^5.50
• Transmembrane helix 6: F^6.44xxxY^6.46
• Transmembrane helix 7: H^7.49S^7.50xxL^7.53

Numbering is according to the Balleros-Weinstein system^[16]

Unlike in Class A GPCRs, in transmembrane helix 4 no DRY^[17] motif was found as well as position 6.50 is not conserved.

Gene

This gene encodes a member of a family of candidate taste receptors that are members of the G protein-coupled receptor superfamily and that are specifically expressed by taste receptor cells of the tongue and palate epithelia. This intronless taste receptor gene encodes a 7-transmembrane receptor protein, functioning as a bitter taste receptor.

SNPs

In T2R1 two SNPs are known in R111H and R206W (dbSNP).

Transcription factors

So far, AML1a, AP-1, AREB6, FOXL1, IRF-7A, Lmo2, NF-E2, NF-E2 p45 were found as the top transcription factor binding sites by QIAGEN in the TAS2R1 gene promoter.

Mutagenesis data

Several mutations have been shown to influence binding of a ligand to TAS2R1 (based on BitterDB):

Receptor region	BW number	Residue	Reference
TM1	1.5	N24	[18][19]
TM1	1.53	I27	[18][19]
TM2	2.5	R55	[18][19]
TM2	2.56	F61	[19]
TM2	2.61	N66	[20][18][8][19]
ECL1		E74	[20]
TM3	3.32	L85	[8][21]
TM3	3.33	L86	[8][21]
TM3	3.36	N89	[8][19][18]
TM3	3.37	E90	[8][21]
TM3	3.41	W94	[18][19]
TM3	3.46	L99	[18][19]
TM5	5.46	E182	[8][21]
TM5	5.61	L197	[18][19]
TM5	5.64	S200	[18][19]
TM5	5.65	L201	[18][19]
TM7	7.39	I263	[8][21]
TM7	7.49	H273	[18][19]
TM7	7.53	L277	[18][19]
TM7	7.54	I278	[18][19]

Ligands

Up to now, 39 ligands for T2R1 were identified in BitterDB, among them L-amino acids, peptides, humulones, small molecules etc.^[22]

See also

• Taste receptor