Taste receptor

Taste receptor
Taste receptors of the tongue are present in the taste buds of papillae.
Identifiers
FMA	84662
Anatomical terminology [ edit on Wikidata]

A taste receptor or tastant is a type of cellular receptor that 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". ^[1]

Vertebrate taste receptors are divided into two families:^{[ citation needed ]}

• Type 1, sweet, first characterized in 2001: ^[2] TAS1R2 – TAS1R3
• Type 2, bitter, first characterized in 2000: ^[3] In humans there are 25 known different bitter receptors, in cats there are 12, in chickens there are three, and in mice there are 35 known different bitter receptors. ^[4]

Visual, olfactive, "sapictive" (the perception of tastes), trigeminal (hot, cool), mechanical, all contribute to the perception of taste. Of these, transient receptor potential cation channel subfamily V member 1 (TRPV1) vanilloid receptors are responsible for the perception of heat from some molecules such as capsaicin, and a CMR1 receptor is responsible for the perception of cold from molecules such as menthol, eucalyptol, and icilin. ^[1]

Tissue distribution

The gustatory system consists of taste receptor cells in taste buds. Taste buds, in turn, are contained in structures called papillae. There are three types of papillae involved in taste: fungiform papillae, foliate papillae, and circumvallate papillae. (The fourth type - filiform papillae do not contain taste buds). Beyond the papillae, taste receptors are also in the palate and early parts of the digestive system like the larynx and upper esophagus. There are three cranial nerves that innervate the tongue; the vagus nerve, glossopharyngeal nerve, and the facial nerve. The glossopharyngeal nerve and the chorda tympani branch of the facial nerve innervate the TAS1R and TAS2R taste receptors. Next to the taste receptors in on the tongue, the gut epithelium is also equipped with a subtle chemosensory system that communicates the sensory information to several effector systems involved in the regulation of appetite, immune responses, and gastrointestinal motility. ^[5]

In 2010, researchers found bitter receptors in lung tissue, which cause airways to relax when a bitter substance is encountered. They believe this mechanism is evolutionarily adaptive because it helps clear lung infections, but could also be exploited to treat asthma and chronic obstructive pulmonary disease. ^[6]

The sweet taste receptor (T1R2/T1R3) can be found in various extra-oral organs throughout the human body such as the brain, heart, kidney, bladder, nasal respiratory epithelium and more. In most of the organs, the receptor function is unclear. ^[7] The sweet taste receptor found in the gut and in the pancreas was found to play an important role in the metabolic regulation of the gut carbohydrate-sensing process and in insulin secretion. ^[8] This receptor is also found in the bladder, suggesting that consumption of artificial sweeteners which activates this receptor might cause excessive bladder contraction. ^[9]

Function

Taste helps to identify toxins, maintain nutrition, and regulate appetite, immune responses, and gastrointestinal motility. ^[5] Five basic tastes are recognized today: salty, sweet, bitter, sour, and umami. Salty and sour taste sensations are both detected through ion channels. Sweet, bitter, and umami tastes, however, are detected by way of G protein-coupled taste receptors. ^[10]

In addition, some agents can function as taste modifiers, as miraculin or curculin for sweet or sterubin to mask bitter.

Mechanism of action

The standard bitter, sweet, or umami taste receptor is a G protein-coupled receptor with seven transmembrane domains. Ligand binding at the taste receptors activate second messenger cascades to depolarize the taste cell. Gustducin is the most common taste Gα subunit, having a major role in TAS2R bitter taste reception. Gustducin is a homologue for transducin, a G-protein involved in vision transduction. ^[11] Additionally, taste receptors share the use of the TRPM5 ion channel, as well as a phospholipase PLCβ2. ^[12]

Savory or glutamates (Umami)

The TAS1R1+TAS1R3 heterodimer receptor functions as an umami receptor, responding to L-amino acid binding, especially L-glutamate. ^[2] The umami taste is most frequently associated with the food additive monosodium glutamate (MSG) and can be enhanced through the binding of inosine monophosphate (IMP) and guanosine monophosphate (GMP) molecules. ^{[13] [14]} 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. ^[2] 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. ^{[13] [15]}

Alternative candidate umami taste receptors include splice variants of metabotropic glutamate receptors, mGluR4 and mGluR1, and the NMDA receptor. ^{[10] [16] [17] [18]}

During the evolution of songbirds, the umami taste receptor has undergone structural modifications in the ligand binding site, enabling these birds to sense the sweet taste by this receptor. ^[19]

Sweet

The diagram above depicts the signal transduction pathway of the sweet taste. Object A is a taste bud, object B is one taste cell of the taste bud, and object C is the neuron attached to the taste cell. I. Part I shows the reception of a molecule. 1. Sugar, the first messenger, binds to a protein receptor on the cell membrane. II. Part II shows the transduction of the relay molecules. 2. G Protein-coupled receptors, second messengers, are activated. 3. G Proteins activate adenylate cyclase, an enzyme, which increases the cAMP concentration. Depolarization occurs. 4. The energy, from step 3, is given to activate the K+, potassium, protein channels.III. Part III shows the response of the taste cell. 5. Ca+, calcium, protein channels is activated.6. The increased Ca+ concentration activates neurotransmitter vesicles. 7. The neuron connected to the taste bud is stimulated by the neurotransmitters.

The TAS1R2+TAS1R3 heterodimer receptor functions as the sweet receptor by binding to a wide variety of sugars and sugar substitutes. ^{[2] [20]} TAS1R2+3 expressing cells are found in circumvallate papillae and foliate papillae near the back of the tongue and palate taste receptor cells in the roof of the mouth. ^[2] These cells are shown to synapse upon the chorda tympani and glossopharyngeal nerves to send their signals to the brain. ^{[10] [15]} The TAS1R3 homodimer also functions as a sweet receptor in much the same way as TAS1R2+3 but has decreased sensitivity to sweet substances. Natural sugars are more easily detected by the TAS1R3 receptor than sugar substitutes. This may help explain why sugar and artificial sweeteners have different tastes. ^[21] Genetic polymorphisms in TAS1R3 partly explain the difference in sweet taste perception and sugar consumption between people of African American ancestry and people of European and Asian ancestries. ^{[22] [23]}

Sensing of the sweet taste has changed throughout the evolution of different animals. Mammals sense the sweet taste by transferring the signal through the heterodimer T1R2/T1R3, the sweet taste receptor. In birds, however, the T1R2 monomer does not exist and they sense the sweet taste through the heterodimer T1R1/T1R3, the umami taste receptor, which has gone through modifications during their evolution. A recently conducted study showed that along the evolution stages of songbirds, there was a decrease in the ability to sense the umami taste, and an increase in the ability to sense the sweet taste, whereas the primordial songbird parent could only sense the umami taste. Researchers found a possible explanation for this phenomenon to be a structural change in the ligand binding site of the umami receptor between the sweet taste sensing and non-sensing songbirds. It is assumed that a mutation in the binding site occurred over time, which allowed them to sense the sweet taste through the umami taste receptor. ^[19]

Bitter

The TAS2R proteins (InterPro :  IPR007960 ) function as bitter taste receptors. ^[24] There are 43 human TAS2R genes, each of which (excluding the five pseudogenes) lacks introns and codes for a GPCR protein. ^[10] These proteins, as opposed to TAS1R proteins, have short extracellular domains and are located in circumvallate papillae, palate, foliate papillae, and epiglottis taste buds, with reduced expression in fungiform papillae. ^{[3] [10]} Though it is certain that multiple TAS2Rs are expressed in one taste receptor cell, it is still debated whether mammals can distinguish between the tastes of different bitter ligands. ^{[3] [10]} Some overlap must occur, however, as there are far more bitter compounds than there are TAS2R genes. Common bitter ligands include cycloheximide, denatonium, PROP (6-n-propyl-2-thiouracil), PTC (phenylthiocarbamide), and β-glucopyranosides. ^[10]

Signal transduction of bitter stimuli is accomplished via the α-subunit of gustducin. This G protein subunit activates a taste phosphodiesterase and decreases cyclic nucleotide levels. Further steps in the transduction pathway are still unknown. The βγ-subunit of gustducin also mediates taste by activating IP₃ (inositol triphosphate) and DAG (diglyceride). These second messengers may open gated ion channels or may cause release of internal calcium. ^[25] Though all TAS2Rs are located in gustducin-containing cells, knockout of gustducin does not completely abolish sensitivity to bitter compounds, suggesting a redundant mechanism for bitter tasting ^[12] (unsurprising given that a bitter taste generally signals the presence of a toxin). ^[12] One proposed mechanism for gustducin-independent bitter tasting is via ion channel interaction by specific bitter ligands, similar to the ion channel interaction which occurs in the tasting of sour and salty stimuli. ^[10]

One of the best-researched TAS2R proteins is TAS2R38, which contributes to the tasting of both PROP and PTC. It is the first taste receptor whose polymorphisms are shown to be responsible for differences in taste perception. Current studies are focused on determining other such taste phenotype-determining polymorphisms. ^[10] More recent studies show that genetic polymorphisms in other bitter taste receptor genes influence bitter taste perception of caffeine, quinine and denatonium benzoate. ^[26]

The diagram depicted above shows the signal transduction pathway of the bitter taste. Bitter taste has many different receptors and signal transduction pathways. Bitter indicates poison to animals. It is most similar to sweet. Object A is a taste bud, object B is one taste cell, and object C is a neuron attached to object B. I. Part I is the reception of a molecule.1. A bitter substance such as quinine, is consumed and binds to G Protein-coupled receptors.II. Part II is the transduction pathway 2. Gustducin, a G protein second messenger, is activated. 3. Phosphodiesterase, an enzyme, is then activated. 4. Cyclic nucleotide, cNMP, is used, lowering the concentration 5. Channels such as the K+, potassium, channels, close.III. Part III is the response of the taste cell. 6. This leads to increased levels of Ca+. 7. The neurotransmitters are activated. 8. The signal is sent to the neuron.

It has been demonstrated that bitterness receptors (TAS2R) play an important role in an innate immune system of airway (nose and sinuses) ciliated epithelium tissues. ^[27] This innate immune system adds an "active fortress" ^[28] to the physical Immune system surface barrier. This fixed immune system is activated by the binding of ligands to specific receptors. These natural ligands are bacterial markers, for TAS2R38 example: acyl-homoserine lactones ^[29] or quinolones ^[30] produced by Pseudomonas aeruginosa. To defend against predators, some plants have produced mimic bacterial markers substances. These plant mimes are interpreted by the tongue, and the brain, as being bitterness. The fixed immune system receptors are identical to the bitter taste receptors, TAS2R. Bitterness substances are agonist of TAS2R fixed immune system. ^[27] The innate immune system uses nitric oxide and defensins which are capable of destroying bacteria, and also viruses. ^{[31] [32]} These fixed innate immune systems (Active Fortresses) are known in other epithelial tissues than upper airway (nose, sinuses, trachea, bronchi), for example: breast (mammary epithelial cells), gut and also human skin (keratinocytes) ^[33] Bitter molecules, their associated bitter taste receptors, and the sequences and homology models of bitter taste receptors, are available via BitterDB.

Sour

See also: Taste § Sourness

Historically it was thought that the sour taste was produced solely when free hydrogen ions (H⁺) directly depolarised taste receptors. However, specific receptors for sour taste with other methods of action are now being proposed. The HCN channels were such a proposal; as they are cyclic nucleotide-gated channels. The two ion channels now suggested to contribute to sour taste are ASIC2 and TASK-1.

The diagram depicts the signal transduction pathway of the sour or salty taste. Object A is a taste bud, object B is a taste receptor cell within object A, and object C is the neuron attached to object B. I. Part I is the reception of hydrogen ions or sodium ions. 1. If the taste is sour, H+ ions, from an acidic substances, pass through their specific ion channel. Some can go through the Na+ channels. If the taste is salty Na+, sodium, molecules pass through the Na+ channels. Depolarization takes place II. Part II is the transduction pathway of the relay molecules.2. Cation, such as K+, channels are opened. III. Part III is the response of the cell. 3. An influx of Ca+ ions is activated.4. The Ca+ activates neurotransmitters. 5. A signal is sent to the neuron attached to the taste bud.

Salt

See also: Taste § Saltiness

Various receptors have also been proposed for salty tastes, along with the possible taste detection of lipids, complex carbohydrates, and water. Evidence for these receptors had been unconvincing in most mammal studies. For example, the proposed ENaC receptor for sodium detection can only be shown to contribute to sodium taste in Drosophila. ^[10] However, proteolyzed forms of ENaC have been shown to function as a human salt taste receptor. Proteolysis is the process where a protein is cleaved. The mature form of ENaC is thought to be proteolyzed, however the characterization of which proteolyzed forms exist in which tissues is incomplete. Proteolysis of cells created to overexpress hetermulitmeric ENaC comprising alpha, beta and gamma subunits was used to identify compounds that selectively enhanced the activity of proteolyzed ENaC versus non-proteolyzed ENaC. Human sensory studies demonstrated that a compound that enhances proteolyzed ENaC functions to enhance the salty taste of table salt, or sodium chloride, confirming proteolyzed ENaC as the first human salt taste receptor. ^[34]

Carbonation

An enzyme connected to the sour receptor transmits information about carbonated water. ^[35]

Fat

A possible taste receptor for fat, CD36, has been identified. ^[36] CD36 has been localized to the circumvallate and foliate papillae, which are present in taste buds ^[37] and where lingual lipase is produced, and research has shown that the CD36 receptor binds long chain fatty acids. ^[38] Differences in the amount of CD36 expression in human subjects was associated with their ability to taste fats, ^[39] creating a case for the receptor's relationship to fat tasting. Further research into the CD36 receptor could be useful in determining the existence of a true fat-tasting receptor.

Free fatty acid receptor 4 (also termed GPR120) and to a much lesser extent free fatty acid receptor 1 (also termed GPR40) ^[40] have been implicated to respond to oral fat, ^[41] and their absence leads to reduced fat preference and reduced neuronal response to orally administered fatty acids. ^[42]

TRPM5 has been shown to be involved in oral fat response and identified as a possible oral fat receptor, but recent evidence presents it as primarily a downstream actor. ^{[43] [44]}

Types

Human bitter taste receptor genes are named TAS2R1 to TAS2R64, with many gaps due to non-existent genes, pseudogenes or proposed genes that have not been annotated to the most recent human genome assembly. Many bitter taste receptor genes also have confusing synonym names with several different gene names referring to the same gene. See table below for full list of human bitter taste receptor genes:

Class	Gene	Synonyms	Aliases	Locus	Description
type 1 (sweet)	TAS1R1		GPR70	1p36.23
	TAS1R2		GPR71	1p36.23
	TAS1R3			1p36
type 2 (bitter)	TAS2R1			5p15
	TAS2R2			7p21.3	pseudogene
	TAS2R3			7q31.3-q32
	TAS2R4			7q31.3-q32
	TAS2R5			7q31.3-q32
	TAS2R6			7	not annotated in human genome assembly
	TAS2R7			12p13
	TAS2R8			12p13
	TAS2R9			12p13
	TAS2R10			12p13
	TAS2R11				absent in humans
	TAS2R12	TAS2R26		12p13.2	pseudogene
	TAS2R13			12p13
	TAS2R14			12p13
	TAS2R15			12p13.2	pseudogene
	TAS2R16			7q31.1-q31.3
	TAS2R17				absent in humans
	TAS2R18			12p13.2	pseudogene
	TAS2R19	TAS2R23, TAS2R48		12p13.2
	TAS2R20	TAS2R49		12p13.2
	TAS2R21				absent in humans
	TAS2R22			12	not annotated in human genome assembly
	TAS2R24				absent in humans
	TAS2R25				absent in humans
	TAS2R27				absent in humans
	TAS2R28				absent in humans
	TAS2R29				absent in humans
	TAS2R30	TAS2R47		12p13.2
	TAS2R31	TAS2R44		12p13.2
	TAS2R32				absent in humans
	TAS2R33			12	not annotated in human genome assembly
	TAS2R34				absent in humans
	TAS2R35				absent in humans
	TAS2R36			12	not annotated in human genome assembly
	TAS2R37			12	not annotated in human genome assembly
	TAS2R38			7q34
	TAS2R39			7q34
	TAS2R40		GPR60	7q34
	TAS2R41			7q34
	TAS2R42			12p13
	TAS2R43			12p13.2
	TAS2R45		GPR59	12
	TAS2R46			12p13.2
	TAS2R50	TAS2R51		12p13.2
	TAS2R52				absent in humans
	TAS2R53				absent in humans
	TAS2R54				absent in humans
	TAS2R55				absent in humans
	TAS2R56				absent in humans
	TAS2R57				absent in humans
	TAS2R58				absent in humans
	TAS2R59				absent in humans
	TAS2R60			7
	TAS2R62P			7q34	pseudogene
	TAS2R63P			12p13.2	pseudogene
	TAS2R64P			12p13.2	pseudogene

Loss of function

In many species, taste receptors have shown loss of functions. The evolutionary process in which taste receptors lost their function is believed to be an adaptive evolution where it is associated with feeding ecology to drive specialization and bifurcation of taste receptors. ^[45] Out of all the taste receptors, bitter, sweet, and umami are shown to have a correlation between inactivation of taste receptors and feeding behavior. ^[45] However, there are no strong evidences that support any vertebrates are missing the bitter taste receptor genes. ^[45]

The sweet taste receptor is one of the taste receptors where the function has been lost. In mammals, the predominant sweet taste receptor is the Type 1 taste receptor Tas1r2/Tas1r3. ^[46] Some mammalian species such as cats and vampire bats have shown inability to taste sweet. ^[46] In these species, the cause of loss of function of the sweet receptor is due to the pseudogenization of Tas1r2. ^[46] The pseudogenization of Tas1r2 is also observed in non-mammalian species such as chickens and tongueless Western clawed frog, and these species also show the inability to taste sweet. ^[46] The pseudogenization of Tas1r2 is widespread and independent in the order Carnivora. ^[46] Many studies have shown that the pseudogenization of taste receptors is caused by a deleterious mutation in the open reading frames (ORF). ^[47] In a study, it was found that in nonfeline carnivorous species, these species showed ORF-disrupting mutations of Tas1r2, and they occurred independently among the species. ^[46] They also showed high variance in their lineages. ^[46] It is hypothesized that the pseudogenization of Tas1r2 occurred through convergent evolution where carnivorous species lost their ability to taste sweet because of dietary behavior. ^[46]

Umami is also a taste receptor where the function has been lost in many species. The predominant umami taste receptors are Tas1r1/Tas1r3. ^[46] In two lineages of aquatic mammals including dolphins and sea lions, Tas1r1 has been found to be pseudogenized. ^[46] The pseudogenization of Tas1r1 has also been found in terrestrial, carnivorous species. ^[46] While the panda belongs to the order Carnivora, it is herbivorous where 99% of its diet is bamboo, and it cannot taste umami. ^[48] Genome sequence of the panda shows that its Tas1r1 gene is pseudogenized. ^[48] In a study, it was found that in all species in the order Carnivora except the panda, the open reading frame was maintained. ^[48] In panda, the nonsynonymous to synonymous substitutions ratio was found to be much higher than other species in order Carnivora. ^[48] This data correlates with fossil records date of the panda to show where panda switched from carnivore to herbivore diet. ^[46] Therefore, the loss of function of umami in panda is hypothesized to be caused by dietary change where the panda became less dependence on meat. ^[46] However, these studies do not explain herbivores such as horses and cows that have retained the Tas1r1 receptor. ^[48]

Overall, the loss of function of the a taste receptor is an evolutionary process that occurred due to a dietary change in species. ^[47]

See also

List of distinct cell types in the adult human body

References

1. This, Hervé (2012). "The Science of the Oven - Excerpt from Chapter 1". Archived from the original on 2 May 2014. Retrieved 30 Apr 2014.
2. Nelson G, Hoon MA, Chandrashekar J, et al. (August 2001). "Mammalian sweet taste receptors". Cell. 106 (3): 381–90. doi: 10.1016/S0092-8674(01)00451-2 . PMID   11509186. S2CID   11886074.
3. Adler E, Hoon MA, Mueller KL, et al. (March 2000). "A novel family of mammalian taste receptors". Cell. 100 (6): 693–702. doi: 10.1016/S0092-8674(00)80705-9 . PMID   10761934. S2CID   14604586.
4. "Receptor Search". Bitter DB. Archived from the original on 2024-09-26. Retrieved 2024-10-20.
5. Steensels S, Depoortere I (2018). "Chemoreceptors in the Gut". Annual Review of Physiology. 80: 117–141. doi:10.1146/annurev-physiol-021317-121332. PMID   29029594.
6. Deshpande DA, Wang WC, McIlmoyle EL, et al. (November 2010). "Bitter taste receptors on airway smooth muscle bronchodilate by localized calcium signaling and reverse obstruction". Nature Medicine. 16 (11): 1299–304. doi:10.1038/nm.2237. PMC   3066567 . PMID   20972434.
7. Laffitte, Anni; Neiers, Fabrice; Briand, Loïc (July 2014). "Functional roles of the sweet taste receptor in oral and extraoral tissues". Current Opinion in Clinical Nutrition and Metabolic Care. 17 (4): 379–385. doi:10.1097/mco.0000000000000058. ISSN   1363-1950. PMC   4059820 . PMID   24763065.
8. Henquin, J.-C. (2012-08-21). "Do Pancreatic Cells "Taste" Nutrients to Secrete Insulin?". Science Signaling. 5 (239): pe36. doi:10.1126/scisignal.2003325. ISSN   1945-0877. PMID   22932700. S2CID   206671643.
9. Elliott, Ruth A.; Kapoor, Shalini; Tincello, Douglas G. (December 2011). "Expression and Distribution of the Sweet Taste Receptor Isoforms T1R2 and T1R3 in Human and Rat Bladders". Journal of Urology. 186 (6): 2455–2462. doi:10.1016/j.juro.2011.07.083. hdl: 2381/10362 . ISSN   0022-5347. PMID   22019168.
10. Bachmanov AA, Beauchamp GK (2007). "Taste receptor genes". Annual Review of Nutrition. 27: 389–414. doi:10.1146/annurev.nutr.26.061505.111329. PMC   2721271 . PMID   17444812.
11. Sainz E, Cavenagh MM, LopezJimenez ND, et al. (June 2007). "The G-protein coupling properties of the human sweet and amino acid taste receptors". Developmental Neurobiology. 67 (7): 948–59. doi:10.1002/dneu.20403. PMID   17506496. S2CID   29736077.
12. Zhang Y, Hoon MA, Chandrashekar J, et al. (February 2003). "Coding of sweet, bitter, and umami tastes: different receptor cells sharing similar signaling pathways". Cell. 112 (3): 293–301. doi: 10.1016/S0092-8674(03)00071-0 . PMID   12581520. S2CID   718601.
13. Nelson G, Chandrashekar J, Hoon MA, et al. (March 2002). "An amino-acid taste receptor". Nature. 416 (6877): 199–202. Bibcode:2002Natur.416..199N. doi:10.1038/nature726. PMID   11894099. S2CID   1730089.
14. Delay ER, Beaver AJ, Wagner KA, et al. (October 2000). "Taste preference synergy between glutamate receptor agonists and inosine monophosphate in rats". Chemical Senses. 25 (5): 507–15. doi: 10.1093/chemse/25.5.507 . PMID   11015322.
15. Danilova V, Hellekant G (March 2003). "Comparison of the responses of the chorda tympani and glossopharyngeal nerves to taste stimuli in C57BL/6J mice". BMC Neuroscience. 4: 5. doi: 10.1186/1471-2202-4-5 . PMC   153500 . PMID   12617752.
16. Brand JG (April 2000). "Receptor and transduction processes for umami taste". The Journal of Nutrition. 130 (4S Suppl): 942S–5S. doi: 10.1093/jn/130.4.942S . PMID   10736357.
17. Chaudhari N, Landin AM, Roper SD (February 2000). "A metabotropic glutamate receptor variant functions as a taste receptor". Nature Neuroscience. 3 (2): 113–9. doi:10.1038/72053. PMID   10649565. S2CID   16650588.
18. Toyono T, Seta Y, Kataoka S, et al. (July 2003). "Expression of metabotropic glutamate receptor group I in rat gustatory papillae". Cell and Tissue Research. 313 (1): 29–35. doi:10.1007/s00441-003-0740-2. PMID   12898387. S2CID   41546387.
19. Toda, Yasuka; Ko, Meng-Ching; Liang, Qiaoyi; et al. (2021-07-08). "Early origin of sweet perception in the songbird radiation". Science. 373 (6551): 226–231. Bibcode:2021Sci...373..226T. doi:10.1126/science.abf6505. ISSN   0036-8075. PMID   34244416. S2CID   235769720.
20. Li X, Staszewski L, Xu H, et al. (April 2002). "Human receptors for sweet and umami taste". Proceedings of the National Academy of Sciences of the United States of America. 99 (7): 4692–6. Bibcode:2002PNAS...99.4692L. doi: 10.1073/pnas.072090199 . PMC   123709 . PMID   11917125.
21. Zhao GQ, Zhang Y, Hoon MA, et al. (October 2003). "The receptors for mammalian sweet and umami taste". Cell. 115 (3): 255–66. doi: 10.1016/S0092-8674(03)00844-4 . PMID   14636554. S2CID   11773362.
22. Hwang LD, Lin C, Gharahkhani P, et al. (April 2019). "New insight into human sweet taste: a genome-wide association study of the perception and intake of sweet substances". American Journal of Clinical Nutrition. 109 (6): 1724–1737. doi:10.1093/ajcn/nqz043. PMC   6537940 . PMID   31005972.
23. Yousif R (March 2020). "Exploring the Molecular Interactions between Neoculin and the Human Sweet Taste Receptors through Computational Approaches" (PDF). Sains Malaysiana. 49 (3): 517–525. doi: 10.17576/jsm-2020-4903-06 .
24. Chandrashekar J, Mueller KL, Hoon MA, et al. (March 2000). "T2Rs function as bitter taste receptors". Cell. 100 (6): 703–11. doi: 10.1016/S0092-8674(00)80706-0 . PMID   10761935. S2CID   7293493.
25. Margolskee RF (January 2002). "Molecular mechanisms of bitter and sweet taste transduction". The Journal of Biological Chemistry. 277 (1): 1–4. doi: 10.1074/jbc.R100054200 . PMID   11696554.
26. Hwang LD, Gharahkhani P, Breslin PA, et al. (September 2018). "Bivariate genome-wide association analysis strengthens the role of bitter receptor clusters on chromosomes 7 and 12 in human bitter taste". BMC Genomics. 19 (1): 678. doi: 10.1186/s12864-018-5058-2 . PMC   6142396 . PMID   30223776.
27. Lee RJ, Cohen, NA (2015). "Taste receptors in innate immunity". Cell. Mol. Life Sci. 72 (2): 217–236. doi:10.1007/s00018-014-1736-7. PMC   4286424 . PMID   25323130.
28. "Le système immunitaire fixe, les TAS2R" (in French). September 4, 2020.
29. Lee RJ, Cohen, NA (2015). "Role of the bitter taste receptor T2R38 in upper respiratory infection and chronic rhinosinusitis". Current Opinion in Allergy and Clinical Immunology. 15 (1): 14–20. doi:10.1097/ACI.0000000000000120. PMC   5902169 . PMID   25304231.
30. Freund J, Mansfield CJ, Doghramji LJ, and Lee RJ (2018). "Activation of airway epithelial bitter taste receptors by Pseudomonas aeruginosa quinolones modulates calcium, cyclic-AMP, and nitric oxide signaling". Journal of Biological Chemistry. 293 (25): 9824–9840. doi: 10.1074/jbc.RA117.001005 . PMC   6016477 . PMID   29748385.
31. Klotman ME, Chang TL (June 2006). "Defensins in innate antiviral immunity". Nature Reviews. Immunology. 6 (6): 447–56. doi:10.1038/nri1860. PMID   16724099. S2CID   8603587.
32. Croen K (1993). "Evidence for antiviral effect of nitric oxide. Inhibition of herpes simplex virus type 1 replication". The Journal of Clinical Investigation. 91 (6): 2446–2452. doi:10.1172/JCI116479. PMC   443304 . PMID   8390481.
33. Woelfle U, Elsholz F (2015). "Expression and Functional Activity of the Bitter Taste Receptors TAS2R1 and TAS2R38 in Human Keratinocytes". Skin Pharmacology and Physiology. 28 (3): 137–146. doi:10.1159/000367631. PMID   25573083. S2CID   19912094.
34. Shekdar K, Langer J, Venkatachalan S, et al. (March 2021). "Cell engineering method using fluorogenic oligonucleotide signaling probes and flow cytometry". Biotechnology Letters. 43 (5): 949–958. doi:10.1007/s10529-021-03101-5. ISSN   0141-5492. PMC   7937778 . PMID   33683511.
35. "Scientists Discover Protein Receptor for Carbonation Taste, October 15, 2009 News Release - National Institutes of Health (NIH)". Archived from the original on 2015-07-03. Retrieved 2014-10-06.
36. Laugerette F, Passilly-Degrace P, Patris B, et al. (November 2005). "CD36 involvement in orosensory detection of dietary lipids, spontaneous fat preference, and digestive secretions". The Journal of Clinical Investigation. 115 (11): 3177–84. doi:10.1172/JCI25299. PMC   1265871 . PMID   16276419.
37. Simons PJ, Kummer JA, Luiken JJ, Boon L (December 2011). "Apical CD36 immunolocalization in human and porcine taste buds from circumvallate and foliate papillae". Acta Histochemica. 113 (8): 839–43. doi:10.1016/j.acthis.2010.08.006. PMID   20950842.
38. Baillie AG, Coburn CT, Abumrad NA (September 1996). "Reversible binding of long-chain fatty acids to purified FAT, the adipose CD36 homolog". The Journal of Membrane Biology. 153 (1): 75–81. doi:10.1007/s002329900111. PMID   8694909. S2CID   5911289.
39. Pepino MY, Love-Gregory L, Klein S, Abumrad NA (March 2012). "The fatty acid translocase gene CD36 and lingual lipase influence oral sensitivity to fat in obese subjects". Journal of Lipid Research. 53 (3): 561–6. doi: 10.1194/jlr.M021873 . PMC   3276480 . PMID   22210925.
40. Kimura I, Ichimura A, Ohue-Kitano R, Igarashi M (January 2020). "Free Fatty Acid Receptors in Health and Disease". Physiological Reviews. 100 (1): 171–210. doi: 10.1152/physrev.00041.2018 . PMID   31487233.
41. DiPatrizio NV (September 2014). "Is fat taste ready for primetime?". Physiology & Behavior. 136: 145–54. doi:10.1016/j.physbeh.2014.03.002. PMC   4162865 . PMID   24631296.
42. Cartoni C, Yasumatsu K, Ohkuri T, et al. (June 2010). "Taste preference for fatty acids is mediated by GPR40 and GPR120". The Journal of Neuroscience. 30 (25): 8376–82. doi:10.1523/JNEUROSCI.0496-10.2010. PMC   6634626 . PMID   20573884.
43. Mattes RD (September 2011). "Accumulating evidence supports a taste component for free fatty acids in humans". Physiology & Behavior. 104 (4): 624–31. doi:10.1016/j.physbeh.2011.05.002. PMC   3139746 . PMID   21557960.
44. Liu P, Shah BP, Croasdell S, Gilbertson TA (June 2011). "Transient receptor potential channel type M5 is essential for fat taste". The Journal of Neuroscience. 31 (23): 8634–42. doi:10.1523/JNEUROSCI.6273-10.2011. PMC   3125678 . PMID   21653867.
45. Feng P, Zhao H (June 2013). "Complex evolutionary history of the vertebrate sweet/umami taste receptor genes". Chinese Science Bulletin. 58 (18): 2198–2204. Bibcode:2013ChSBu..58.2198F. doi: 10.1007/s11434-013-5811-5 .
46. Jiang P, Josue J, Li X, et al. (March 2012). "Major taste loss in carnivorous mammals". Proceedings of the National Academy of Sciences of the United States of America. 109 (13): 4956–61. doi: 10.1073/pnas.1118360109 . PMC   3324019 . PMID   22411809.
47. Antinucci M, Risso D (2017-11-28). "A Matter of Taste: Lineage-Specific Loss of Function of Taste Receptor Genes in Vertebrates". Frontiers in Molecular Biosciences. 4: 81. doi: 10.3389/fmolb.2017.00081 . PMC   5712339 . PMID   29234667.
48. Zhao H, Yang JR, Xu H, Zhang J (December 2010). "Pseudogenization of the umami taste receptor gene Tas1r1 in the giant panda coincided with its dietary switch to bamboo". Molecular Biology and Evolution. 27 (12): 2669–73. doi:10.1093/molbev/msq153. PMC   3108379 . PMID   20573776.

External links

• Adler E, Hoon MA, Mueller KL, et al. (2000). "A Novel Family of Mammalian Taste Receptors - An Investigative Review". Davidson College Biology Department. Retrieved 2008-08-11.
• taste+receptors,+type+1 at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
• taste+receptors,+type+2 at the U.S. National Library of Medicine Medical Subject Headings (MeSH)