# TAS1R1

## Overview
The TAS1R1 gene encodes the taste 1 receptor member 1 protein, which is a critical component of the umami taste perception system. This protein is a G protein-coupled receptor (GPCR) that forms a heterodimer with TAS1R3, enabling the detection of amino acids such as glutamate, a key component of the umami taste. The TAS1R1/TAS1R3 complex is primarily expressed in the taste buds of the tongue, where it plays a significant role in taste signal transduction. Beyond its role in taste, TAS1R1 is involved in broader physiological processes, including the mammalian target of rapamycin complex 1 (mTORC1) signaling pathway, which is important for protein synthesis regulation. Variations in the TAS1R1 gene have been linked to differences in taste sensitivity and dietary preferences, as well as potential implications in health conditions such as gastric cancer and lung adenocarcinoma (Zhou2018Methionine; Valente2018Genes; Carey2022Impact).

## Structure
The TAS1R1 protein is a G protein-coupled receptor (GPCR) involved in umami taste perception. It forms a heterodimer with TAS1R3, which is essential for its function in detecting amino acids like glutamic acid. The primary structure of TAS1R1 consists of a sequence of amino acids that contribute to its functional conformation. The secondary structure includes alpha helices and beta sheets, which are typical of GPCRs. The tertiary structure refers to the three-dimensional conformation of the protein, which is crucial for its interaction with ligands and other proteins. In terms of quaternary structure, TAS1R1 interacts with TAS1R3 to form a functional receptor complex.

TAS1R1 contains a Venus flytrap domain, a characteristic feature of class C GPCRs, which is involved in ligand binding. This domain undergoes conformational changes upon ligand binding, which is critical for signal transduction. Post-translational modifications, such as glycosylation, may occur, influencing the protein's stability and function. These structural features enable TAS1R1 to effectively participate in taste perception by detecting specific amino acids and activating downstream signaling pathways (Zhou2018Methionine; Kim2015A).

## Function
The TAS1R1 gene encodes a protein that forms a heterodimer with TAS1R3, functioning as an umami taste receptor. This receptor is part of the seven-transmembrane G-protein-coupled receptors (GPCRs) superfamily and is crucial for the perception of umami taste, which is associated with the detection of amino acids, particularly glutamate, in foods (Li2002Human; Valente2018Genes). The TAS1R1/TAS1R3 complex specifically responds to L-glutamate, with its response enhanced by 5'-ribonucleotides like inosine monophosphate (IMP), which are characteristic of umami taste (Li2002Human; Chen2009Perceptual).

This receptor complex is expressed in the fungiform and circumvallate papillae of the tongue, where it plays a role in taste transduction mechanisms (Rawal2013Do). The TAS1R1 gene has undergone positive selection in human evolution, likely due to dietary changes such as the introduction of cooked food, which may have provided a selective advantage by enhancing umami taste perception (Valente2018Genes). Variants in the TAS1R1 gene have been linked to differences in umami sensitivity among individuals, contributing to variations in taste perception and dietary preferences (Chen2009Perceptual).

## Clinical Significance
Mutations and alterations in the expression of the TAS1R1 gene have been associated with various health conditions, particularly in the context of cancer. In a Korean population, genetic variants in TAS1R1 have been linked to dietary habits and gastric cancer (GC) risk. Specifically, the TAS1R1 rs34160967 variant is associated with an increased risk of GC in males, independent of dietary intake, suggesting its potential role as a marker for GC susceptibility (Choi2016Variations). This variant may affect umami taste perception and alter physiological processes related to digestion and immunity, which could influence GC risk (Choi2016Variations).

In the context of solid tumors, TAS1R1 expression has been found to vary across different cancer types. Increased expression of TAS1R1 is associated with improved survival in lung adenocarcinoma, indicating its potential as a prognostic biomarker for cancer outcomes (Carey2022Impact). These findings suggest that TAS1R1 may play a role in cancer prognosis and could be considered in treatment selection strategies (Carey2022Impact). However, the exact mechanisms by which TAS1R1 influences these conditions remain to be fully elucidated.

## Interactions
The TAS1R1 protein forms a heterodimer with TAS1R3, creating a functional receptor complex primarily responsible for detecting umami taste stimuli, such as L-glutamate. This interaction is crucial for the receptor's ability to respond to amino acids, with the presence of 5'-ribonucleotides like inosine monophosphate (IMP) enhancing the receptor's response by stabilizing its active conformation (Li2002Human; Behrens2016G). The TAS1R1/TAS1R3 complex is a type of G protein-coupled receptor (GPCR) that interacts with G-protein subunits, particularly gustducin, to transduce taste signals (Behrens2016G).

In addition to its role in taste perception, TAS1R1 is involved in the mammalian target of rapamycin complex 1 (mTORC1) signaling pathway. In bovine mammary epithelial cells, TAS1R1, as part of the TAS1R1/TAS1R3 receptor, senses extracellular amino acids and activates mTORC1 signaling by increasing intracellular calcium levels. This interaction is significant for protein synthesis regulation, particularly in response to amino acid availability (Zhou2018Methionine). The receptor's ability to sense amino acids and influence intracellular signaling pathways highlights its broader role beyond taste perception.


## References


[1. (Rawal2013Do) S. Rawal, J. E. Hayes, M. R. Wallace, L. M. Bartoshuk, and V. B. Duffy. Do polymorphisms in the tas1r1 gene contribute to broader differences in human taste intensity? Chemical Senses, 38(8):719–728, September 2013. URL: http://dx.doi.org/10.1093/chemse/bjt040, doi:10.1093/chemse/bjt040. This article has 20 citations and is from a peer-reviewed journal.](https://doi.org/10.1093/chemse/bjt040)

[2. (Behrens2016G) Maik Behrens and Wolfgang Meyerhof. G Protein–Coupled Taste Receptors, pages 227–244. Elsevier, 2016. URL: http://dx.doi.org/10.1016/b978-0-12-801694-7.00013-5, doi:10.1016/b978-0-12-801694-7.00013-5. This article has 10 citations.](https://doi.org/10.1016/b978-0-12-801694-7.00013-5)

[3. (Valente2018Genes) Cristina Valente, Luis Alvarez, Patrícia Isabel Marques, Leonor Gusmão, António Amorim, Susana Seixas, and Maria João Prata. Genes from the tas1r and tas2r families of taste receptors: looking for signatures of their adaptive role in human evolution. Genome Biology and Evolution, 10(4):1139–1152, April 2018. URL: http://dx.doi.org/10.1093/gbe/evy071, doi:10.1093/gbe/evy071. This article has 19 citations and is from a domain leading peer-reviewed journal.](https://doi.org/10.1093/gbe/evy071)

[4. (Zhou2018Methionine) Y. Zhou, Z. Zhou, J. Peng, and J.J. Loor. Methionine and valine activate the mammalian target of rapamycin complex 1 pathway through heterodimeric amino acid taste receptor (tas1r1/tas1r3) and intracellular ca2+ in bovine mammary epithelial cells. Journal of Dairy Science, 101(12):11354–11363, December 2018. URL: http://dx.doi.org/10.3168/jds.2018-14461, doi:10.3168/jds.2018-14461. This article has 43 citations and is from a highest quality peer-reviewed journal.](https://doi.org/10.3168/jds.2018-14461)

[5. (Kim2015A) J. M. Kim, D. Ren, A. Reverter, and E. Roura. A regulatory gene network related to the porcine umami taste receptor (<scp>tas</scp>1r1/<scp>tas</scp>1r3). Animal Genetics, 47(1):114–119, November 2015. URL: http://dx.doi.org/10.1111/age.12374, doi:10.1111/age.12374. This article has 5 citations and is from a domain leading peer-reviewed journal.](https://doi.org/10.1111/age.12374)

[6. (Carey2022Impact) Ryan M. Carey, TaeBeom Kim, Noam A. Cohen, Robert J. Lee, and Kevin T. Nead. Impact of sweet, umami, and bitter taste receptor (tas1r and tas2r) genomic and expression alterations in solid tumors on survival. Scientific Reports, May 2022. URL: http://dx.doi.org/10.1038/s41598-022-12788-z, doi:10.1038/s41598-022-12788-z. This article has 10 citations and is from a peer-reviewed journal.](https://doi.org/10.1038/s41598-022-12788-z)

[7. (Choi2016Variations) Jeong‐Hwa Choi, Jeonghee Lee, Il Ju Choi, Young‐Woo Kim, Keun Won Ryu, and Jeongseon Kim. Variations in tas1r taste receptor gene family modify food intake and gastric cancer risk in a korean population. Molecular Nutrition &amp; Food Research, 60(11):2433–2445, August 2016. URL: http://dx.doi.org/10.1002/mnfr.201600145, doi:10.1002/mnfr.201600145. This article has 18 citations.](https://doi.org/10.1002/mnfr.201600145)

[8. (Li2002Human) Xiaodong Li, Lena Staszewski, Hong Xu, Kyle Durick, Mark Zoller, and Elliot Adler. Human receptors for sweet and umami taste. Proceedings of the National Academy of Sciences, 99(7):4692–4696, March 2002. URL: http://dx.doi.org/10.1073/pnas.072090199, doi:10.1073/pnas.072090199. This article has 1089 citations.](https://doi.org/10.1073/pnas.072090199)

[9. (Chen2009Perceptual) Qing-Ying Chen, Suzanne Alarcon, Anilet Tharp, Osama M Ahmed, Nelsa L Estrella, Tiffani A Greene, Joseph Rucker, and Paul AS Breslin. Perceptual variation in umami taste and polymorphisms in tas1r taste receptor genes. The American Journal of Clinical Nutrition, 90(3):770S-779S, September 2009. URL: http://dx.doi.org/10.3945/ajcn.2009.27462n, doi:10.3945/ajcn.2009.27462n. This article has 112 citations.](https://doi.org/10.3945/ajcn.2009.27462n)