| TAS1R1 | |||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Aliases | TAS1R1 , GPR70, T1R1, TR1, GM148, taste 1 receptor member 1 | ||||||||||||||||||||||||||||||||||||||||||||||||||
| External IDs | OMIM: 606225 MGI: 1927505 HomoloGene: 12888 GeneCards: TAS1R1 | ||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| Wikidata | |||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
Taste receptor type 1 member 1 is a protein that in humans is encoded by the TAS1R1 gene. [5]
The protein encoded by the TAS1R1 gene is a G protein-coupled receptor with seven trans-membrane domains and is a component of the heterodimeric amino acid taste receptor T1R1+3. This receptor is formed as a dimer of the TAS1R1 and TAS1R3 proteins. Moreover, the TAS1R1 protein is not functional outside of formation of the 1+3 heterodimer. [6] The TAS1R1+3 receptor has been shown to respond to L-amino acids but not to their D-enantiomers or other compounds. This ability to bind L-amino acids, specifically L-glutamine, enables the body to sense the umami, or savory, taste. [7] Multiple transcript variants encoding several different isoforms have been found for this gene, which may account for differing taste thresholds among individuals for the umami taste. [5] [8] Another interesting quality of the TAS1R1 and TAS1R2 proteins is their spontaneous activity in the absence of the extracellular domains and binding ligands. [9] This may mean that the extracellular domain regulates function of the receptor by preventing spontaneous action as well as binding to activating ligands such as L-glutamine.
The umami taste is distinctly related to the compound monosodium glutamate (MSG). Synthesized in 1908 by Japanese chemist Kikunae Ikeda, this flavor-enhancing compound led to the naming of a new flavor quality that was named “umami”, the Japanese word for “tasty”. [10] The TAS1R1+3 taste receptor is sensitive to the glutamate in MSG as well as the synergistic taste-enhancer molecules inosine monophosphate (IMP) and guanosine monophosphate (GMP). These taste-enhancer molecules are unable to activate the receptor alone, but are rather used to enhance receptor responses to many L-amino acids. [7] [11]
TAS1R1 and TAS1R2 receptors have been shown to bind to G proteins, most often the gustducin Gα subunit, although a gustducin knock-out has shown small residual activity. TAS1R1 and TAS1R2 have also been shown to activate Gαo and Gαi. [9] This suggests that TAS1R1 and TAS1R2 are G protein-coupled receptors that inhibit adenylyl cyclases to decrease cyclic guanosine monophosphate (cGMP) levels in taste receptors. [12]
Research done by creating knock-outs of common channels activated by sensory G-protein second messenger systems has also shown a connection between umami taste perception and the phosphatidylinositol (PIP2) pathway. The nonselective cation Transient Receptor Potential channel TRPM5 has been shown to correlate with both umami and sweet taste. Also, the phospholipase PLCβ2 was shown to similarly correlate with umami and sweet taste. This suggests that activation of the G-protein pathway and subsequent activation of PLC β2 and the TRPM5 channel in these taste cells functions to activate the cell. [13]
TAS1R1+3 expressing cells are found mostly in the fungiform papillae at the tip and edges of the tongue and palate taste receptor cells in the roof of the mouth. [6] These cells are shown to synapse upon the chorda tympani nerves to send their signals to the brain, although some activation of the glossopharyngeal nerve has been found. [7] [14] TAS1R and TAS2R (bitter) channels are not expressed together in taste buds. [6]
Umami, or savoriness, is one of the five basic tastes. It has been described as savory and is characteristic of broths and cooked meats.
TAS2R16 is a human gene that encodes for a receptor that may play a role in the perception of bitterness.
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 locations. Molecules which give a sensation of taste are considered "sapid".
Taste receptor type 2 member 1 (TAS2R1/T2R1) is a protein that in humans is encoded by the TAS2R1 gene. 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. 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.
Taste receptor type 2 member 3 is a protein that in humans is encoded by the TAS2R3 gene.
Taste receptor type 2 member 4 is a protein that in humans is encoded by the TAS2R4 gene.
Taste receptor type 2 member 8 is a protein that in humans is encoded by the TAS2R8 gene.
Taste receptor type 2 member 9 is a protein that in humans is encoded by the TAS2R9 gene.
Taste receptor type 2 member 10 is a protein that in humans is encoded by the TAS2R10 gene. The protein is responsible for bitter taste recognition in mammals. It serves as a defense mechanism to prevent consumption of toxic substances which often have a characteristic bitter taste.
Taste receptor type 2 member 13 is a protein that in humans is encoded by the TAS2R13 gene.
Taste receptor type 2 member 5 is a protein that in humans is encoded by the TAS2R5 gene.
Taste receptor type 2 member 7 is a protein that in humans is encoded by the TAS2R7 gene.
Taste receptor type 1 member 2 is a protein that in humans is encoded by the TAS1R2 gene.
Taste receptor type 1 member 3 is a protein that in humans is encoded by the TAS1R3 gene. The TAS1R3 gene encodes the human homolog of mouse Sac taste receptor, a major determinant of differences between sweet-sensitive and -insensitive mouse strains in their responsiveness to sucrose, saccharin, and other sweeteners.
Taste receptor type 2 member 39 is a protein that in humans is encoded by the TAS2R39 gene.
Taste receptor type 2 member 40 is a protein that in humans is encoded by the TAS2R40 gene.
Taste receptor type 2 member 45 is a protein that in humans is encoded by the TAS2R45 gene.
Taste receptor type 2 member 30 is a protein that in humans is encoded by the TAS2R30 gene.
Taste receptor type 2 member 50 is a protein that in humans is encoded by the TAS2R50 gene.
Taste receptor type 2 member 60 is a protein that in humans is encoded by the TAS2R60 gene.
This article incorporates text from the United States National Library of Medicine, which is in the public domain.
