Entry Name Taste transduction - Rattus norvegicus (rat)
Description Five basic tastes are recognized by humans and most other animals - bitter, sweet, sour, salty and umami. In vertebrates, taste stimuli are detected by taste receptor cells (TRCs). At least three distinct cell types are found in mammalian taste buds : type I cells, type II cells, and type III cells. Type I cells express epithelial sodium channel (ENaC) and are considered to be the major mediator of perception of low salt. In type II cells, transduction of bitter, sweet and umami is mediated by a canonical PLC-beta/IP3-signaling cascade, which culminates in the opening of the TRPM5 ion channel. This produces a depolarization that may allow CALMH1 channels to open and release ATP, which serves as a neurotransmitter to activate closely associated nerve afferents expressing P2X2, P2X3 receptors and adjacent type III cells expressing P2Y4 receptors. Type II taste cells also secrete acetylcholine (ACh) that appears to stimulate muscarinic receptors, specifically M3, on the same or neighboring Type II cells. This muscarinic feedback augments taste-evoked release of ATP. In type III cells, sour taste is initiated when protons enter through apically located proton-selective ion channels: polycystic kidney disease 2-like 1 protein (PKD2L1) and polycystic kidney disease 1-like 3 protein (PKD1L3) channels. Weak acids may also activate sour cells by penetrating the cell membrane and leading to closure of resting K+ channels and membrane depolarization. Further, voltage-gated Ca2+ channels are activated and release vesicular serotonin (5-HT), norepinephrine (NE) and gamma-aminobutyric acid (GABA). 5-HT and GABA provide negative paracrine feedback onto receptor cells by activating 5-HT1A and GABAA, GABAB receptors, respectively. 5-HT also functions as a transmitter between presynaptic cells and the sensory afferent.
Class Organismal Systems; Sensory systemBRITE hierarchy
Pathway map Other DBs Organism Rattus norvegicus (rat) [GN:
rno ]
Gene 140675 Gabra4; gamma-aminobutyric acid receptor subunit alpha-4 precursor [KO:K05175 ]
170634 Tas1r3; taste receptor type 1 member 3 precursor [KO:K04626 ]
24239 Cacna1c; voltage-dependent L-type calcium channel subunit alpha-1C [KO:K04850 ]
24260 Chrm3; muscarinic acetylcholine receptor M3 [KO:K04131 ]
24414 Grm1; metabotropic glutamate receptor 1 isoform alpha precursor [KO:K04603 ]
24417 Grm4; metabotropic glutamate receptor 4 precursor [KO:K04607 ]
24473 Htr1a; 5-hydroxytryptamine receptor 1A [KO:K04153 ]
246219 Tas2r126; taste receptor type 2 member 41 [KO:K08474 ]
24654 Plcb1; 1-phosphatidylinositol 4,5-bisphosphate phosphodiesterase beta-1 [KO:K05858 ] [EC:3.1.4.11 ]
24766 Scn2a; sodium channel protein type 2 subunit alpha [KO:K04834 ]
24767 Scnn1b; amiloride-sensitive sodium channel subunit beta [KO:K04825 ]
24768 Scnn1g; amiloride-sensitive sodium channel subunit gamma [KO:K04827 ]
24947 Gabra3; gamma-aminobutyric acid receptor subunit alpha-3 precursor [KO:K05175 ]
25031 Plcb4; 1-phosphatidylinositol 4,5-bisphosphate phosphodiesterase beta-4 [KO:K05858 ] [EC:3.1.4.11 ]
25075 Htr1b; 5-hydroxytryptamine receptor 1B [KO:K04153 ]
25122 Scnn1a; amiloride-sensitive sodium channel subunit alpha [KO:K04824 ]
25323 Htr1d; 5-hydroxytryptamine receptor 1D [KO:K04153 ]
25364 Asic2; acid-sensing ion channel 2 isoform MDEG1 [KO:K04828 ]
25398 Cacna1a; voltage-dependent P/Q-type calcium channel subunit alpha-1A [KO:K04344 ]
25679 Itpr3; inositol 1,4,5-trisphosphate receptor type 3 [KO:K04960 ]
286924 Gnat3; guanine nucleotide-binding protein G(t) subunit alpha-3 [KO:K19729 ]
287003 Tas2r123; taste receptor type 2 member 123 [KO:K08474 ]
289606 Gabra2; gamma-aminobutyric acid receptor subunit alpha-2 precursor [KO:K05175 ]
29322 Plcb3; 1-phosphatidylinositol 4,5-bisphosphate phosphodiesterase beta-3 [KO:K05858 ] [EC:3.1.4.11 ]
293937 Pkd2l1; polycystic kidney disease 2-like 1 protein isoform 1 [KO:K04990 ]
29407 Tas1r1; taste receptor type 1 member 1 precursor [KO:K04624 ]
295589 Tas2r134; taste receptor type 2 member 134 [KO:K08474 ]
29691 Pde1b; dual specificity calcium/calmodulin-dependent 3',5'-cyclic nucleotide phosphodiesterase 1B [KO:K13755 ] [EC:3.1.4.17 ]
29705 Gabra1; gamma-aminobutyric acid receptor subunit alpha-1 precursor [KO:K05175 ]
29707 Gabra5; gamma-aminobutyric acid receptor subunit alpha-5 precursor [KO:K05175 ]
29708 Gabra6; gamma-aminobutyric acid receptor subunit alpha-6 precursor [KO:K05175 ]
364241 Kcnk5; potassium channel subfamily K member 5 [KO:K04916 ]
365391 Trpm5; transient receptor potential cation channel subfamily M member 5 [KO:K04980 ]
497770 Scn3a; sodium channel protein type 3 subunit alpha [KO:K04836 ]
499367 Calhm1; calcium homeostasis modulator protein 1 [KO:K19738 ]
500033 Tas2r7l; taste receptor type 2 member 7-like [KO:K08474 ]
500091 Tas2r138; taste receptor type 2 member 38 [KO:K08474 ]
500101 Tas2r144; taste receptor type 2 member 40 [KO:K08474 ]
500347 Tas2r102; taste receptor type 2 member 102 [KO:K08474 ]
502756 Tas2r143; taste receptor type 2 member 143 [KO:K08474 ]
502757 Tas2r135; taste receptor type 2 member 135 [KO:K08474 ]
58963 Htr3b; 5-hydroxytryptamine receptor 3B precursor [KO:K04819 ]
59266 Hcn4; potassium/sodium hyperpolarization-activated cyclic nucleotide-gated channel 4 [KO:K04957 ]
60448 Htr1f; 5-hydroxytryptamine receptor 1F [KO:K04153 ]
60449 Gnb3; guanine nucleotide-binding protein G(I)/G(S)/G(T) subunit beta-3 [KO:K07825 ]
64467 Entpd2; ectonucleoside triphosphate diphosphohydrolase 2 precursor [KO:K01509 ] [EC:3.6.1.-]
680188 Tas2r139; taste receptor type 2 member 39 [KO:K08474 ]
685451 Gng13; guanine nucleotide-binding protein G(I)/G(S)/G(O) subunit gamma-13 [KO:K04547 ]
689869 Tas2r140; taste receptor type 2 member 140 [KO:K08474 ]
690448 Tas2r120; taste receptor type 2 member 120 [KO:K08474 ]
690472 Tas2r124; taste receptor type 2 member 124 [KO:K08474 ]
690481 Tas2r125; taste receptor type 2 member 125 [KO:K08474 ]
690572 Tas2r109; taste receptor type 2 member 109 [KO:K08474 ]
78956 Scn9a; sodium channel protein type 9 subunit alpha [KO:K04841 ]
78979 Tas2r119; taste receptor type 2 member 119 [KO:K08474 ]
78980 Tas2r118; taste receptor type 2 member 16 [KO:K08474 ]
78981 Tas2r107; taste receptor type 2 member 107 [KO:K08474 ]
78982 Tas2r114; taste receptor type 2 member 114 [KO:K08474 ]
78983 Tas2r121; taste receptor type 2 member 13 [KO:K08474 ]
78984 Tas2r13; taste receptor, type 2, member 13 [KO:K08474 ]
78985 Tas2r105; taste receptor type 2 member 105 [KO:K08474 ]
79246 Htr3a; 5-hydroxytryptamine receptor 3A precursor [KO:K04819 ]
81529 Pde1a; dual specificity calcium/calmodulin-dependent 3',5'-cyclic nucleotide phosphodiesterase 1A [KO:K13755 ] [EC:3.1.4.17 ]
81657 Gabbr1; gamma-aminobutyric acid type B receptor subunit 1 precursor [KO:K04615 ]
81742 Pde1c; dual specificity calcium/calmodulin-dependent 3',5'-cyclic nucleotide phosphodiesterase 1C [KO:K13755 ] [EC:3.1.4.17 ]
83633 Gabbr2; gamma-aminobutyric acid type B receptor subunit 2 precursor [KO:K04615 ]
85240 Plcb2; 1-phosphatidylinositol 4,5-bisphosphate phosphodiesterase beta-2 [KO:K05858 ] [EC:3.1.4.11 ]
Compound C01245 D-myo-Inositol 1,4,5-trisphosphate
C12284 Saccharin sodium anhydrous
D08836 Acesulfame potassium (NF)
Reference Authors Liman ER, Zhang YV, Montell C
Title Peripheral coding of taste.
Journal Reference Authors Kinnamon SC, Finger TE
Title A taste for ATP: neurotransmission in taste buds.
Journal Reference Authors Roper SD
Title Taste buds as peripheral chemosensory processors.
Journal Reference Authors Kinnamon SC
Title Taste receptor signalling - from tongues to lungs.
Journal Reference Authors Kinnamon SC
Title Neurosensory transmission without a synapse: new perspectives on taste signaling.
Journal Reference Authors Chaudhari N, Roper SD
Title The cell biology of taste.
Journal Reference Authors Vandenbeuch A, Kinnamon SC
Title Why do taste cells generate action potentials?
Journal Reference Authors Chandrashekar J, Hoon MA, Ryba NJ, Zuker CS
Title The receptors and cells for mammalian taste.
Journal Reference Authors Vandenbeuch A, Anderson CB, Parnes J, Enjyoji K, Robson SC, Finger TE, Kinnamon SC
Title Role of the ectonucleotidase NTPDase2 in taste bud function.
Journal Reference Authors Taruno A, Vingtdeux V, Ohmoto M, Ma Z, Dvoryanchikov G, Li A, Adrien L, Zhao H, Leung S, Abernethy M, Koppel J, Davies P, Civan MM, Chaudhari N, Matsumoto I, Hellekant G, Tordoff MG, Marambaud P, Foskett JK
Title CALHM1 ion channel mediates purinergic neurotransmission of sweet, bitter and umami tastes.
Journal Reference Authors Gao N, Lu M, Echeverri F, Laita B, Kalabat D, Williams ME, Hevezi P, Zlotnik A, Moyer BD
Title Voltage-gated sodium channels in taste bud cells.
Journal Reference Authors Zheng W, Hussein S, Yang J, Huang J, Zhang F, Hernandez-Anzaldo S, Fernandez-Patron C, Cao Y, Zeng H, Tang J, Chen XZ
Title A novel PKD2L1 C-terminal domain critical for trimerization and channel function.
Journal Reference Authors Shimada S, Ueda T, Ishida Y, Yamamoto T, Ugawa S
Title Acid-sensing ion channels in taste buds.
Journal Reference Authors Dando R, Roper SD
Title Acetylcholine is released from taste cells, enhancing taste signalling.
Journal Reference Authors Kaya N, Shen T, Lu SG, Zhao FL, Herness S
Title A paracrine signaling role for serotonin in rat taste buds: expression and localization of serotonin receptor subtypes.
Journal Related KO pathway
