Taste receptor type 2 member 1 (TAS2R1/T2R1) is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
that in humans is encoded by the ''TAS2R1''
gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...
.
It belongs to the
G protein-coupled receptor
G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-linked receptors (GPLR), form a large group of evolutionarily-related p ...
(GPCR) family and is related to
class A-like GPCRs, they contain 7 transmembrane helix bundles and short
N-terminus loop.
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.
Expression and function
Extra-oral roles of TAS2Rs
Bitter taste receptors are expressed in
taste receptor cells, which organized into
taste bud
Taste buds contain the taste receptor cells, which are also known as gustatory cells. The taste receptors are located around the small structures known as papillae found on the upper surface of the tongue, soft palate, upper esophagus, the c ...
s on the papillae of the
tongue
The tongue is a muscular organ in the mouth of a typical tetrapod. It manipulates food for mastication and swallowing as part of the digestive process, and is the primary organ of taste. The tongue's upper surface (dorsum) is covered by taste ...
and palate epithelium.
In addition, TAS2Rs were found to be expressed in extra-oral tissues, e.g. brain, lungs, gastrointestinal tract, etc.
So far, less is known about their function however, for example it was shown that:
* TAS2Rs mediate relaxation of airway smooth muscles.
* TAS2R43 is involved in secretion of gastric acid in the stomach.
Extra-oral roles of TAS2R1
* TAS2R1, TAS2R4, TAS2R10, TAS2R38 and TAS2R49 were found to be down-regulated in
breast cancer
Breast cancer is cancer that develops from breast tissue. Signs of breast cancer may include a lump in the breast, a change in breast shape, dimpling of the skin, milk rejection, fluid coming from the nipple, a newly inverted nipple, or a r ...
cells''.''
* TAS2R1, causes vasoconstrictor responses in the
pulmonary circuit
The pulmonary circulation is a division of the circulatory system in all vertebrates. The circuit begins with deoxygenated blood returned from the body to the right atrium of the heart where it is pumped out from the right ventricle to the lungs ...
and relaxation in the airways''.''
Structure of TAS2R1 receptor
Based on a recent
homology model
Homology modeling, also known as comparative modeling of protein, refers to constructing an atomic-resolution model of the "''target''" protein from its amino acid sequence and an experimental three-dimensional structure of a related homologous pr ...
fro
BitterDBseveral conserved
motifs, which are counterparts to Class A GPCRs
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.
Unlike in Class A GPCRs, in transmembrane helix 4 no DRY motif was found as well as position 6.50 is not conserved.
''TAS2R1'' gene
This gene encodes a member of a family of candidate
taste receptor
A taste receptor or tastant is a type of cellular receptor which facilitates the sensation of taste. When food or other substances enter the mouth, molecules interact with saliva and are bound to taste receptors in the oral cavity and other loc ...
s that are members of the
G protein-coupled receptor
G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-linked receptors (GPLR), form a large group of evolutionarily-related p ...
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
In genetics, a single-nucleotide polymorphism (SNP ; plural SNPs ) is a germline substitution of a single nucleotide at a specific position in the genome. Although certain definitions require the substitution to be present in a sufficiently larg ...
are known in R111H and R206W (
dbSNP
The Single Nucleotide Polymorphism Database (dbSNP) is a free public archive for genetic variation within and across different species developed and hosted by the National Center for Biotechnology Information (NCBI) in collaboration with the Natio ...
).
Transcription Factors
So far, AML1a, AP-1, AREB6, FOXL1, IRF-7A, Lmo2, NF-E2, NF-E2 p45 were found as the top
transcription factor
In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription of genetic information from DNA to messenger RNA, by binding to a specific DNA sequence. The f ...
binding sites by QIAGEN in th
''TAS2R1'' gene promoter
Mutagenesis
Mutagenesis () is a process by which the genetic information of an organism is changed by the production of a mutation. It may occur spontaneously in nature, or as a result of exposure to mutagens. It can also be achieved experimentally using lab ...
data
Several
mutation
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA replication, DNA or viral repl ...
s have been shown to influence binding of a ligand to TAS2R1 (based o
BitterDB:
Ligands
Up to now, 39 ligands for T2R1 were identified in
BitterDB
The BitterDB is a database of compounds that were reported to taste bitter to humans. The aim of the BitterDB database is to gather information about bitter-tasting natural and synthetic compounds, and their cognate bitter taste receptors (T2Rs ...
, among them
L-amino acids,
peptide
Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides.
...
s,
humulones, small molecules etc.
See also
*
Taste receptor
A taste receptor or tastant is a type of cellular receptor which facilitates the sensation of taste. When food or other substances enter the mouth, molecules interact with saliva and are bound to taste receptors in the oral cavity and other loc ...
References
Further reading
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{{NLM content
Human taste receptors