Pathway Human Homo sapiens

Sensory perception of taste

R-HSA-9717189 in Reactome release 97: under Sensory Perception, with 47 genes placed in it by the mapping files and 3 child pathways in the hierarchy.

The same number in the other species

Reactome writes the mouse and rat events it infers from a human pathway under the human number with the species token. A door opens only where that species' own list in this release holds the id: R-MMU-9717189 (mouse), R-RNO-9717189 (rat). Whether the event was inferred from this one is what the record says.

The record
The genes
Parents and children

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01The record

Reactome's own record of this pathway

What this tells you

The pathway list, the hierarchy and the genes on this page are read from the files Reactome publishes for Reactome release 97, built into this site on 2026-09-09: the pathway list, the hierarchy relationship file and the two gene mapping files. The record card is the one live read, Reactome's own record of this pathway.

Reactome's download page describes the mapping files: Mapping files link the source database identifier to the lowest level pathway diagram or subset of the pathway, all levels of the pathway hierarchy or database identifier to all reactions. [R13] The gene list here is the all-levels mapping of NCBI Gene ids, filled from the all-levels mapping of Ensembl ids where the NCBI file has no row for a gene; each row names which file it came from by the shape of its source id. Each row carries the evidence codes the file writes for it, as written and unranked, and both where the file writes both; no page of Reactome's documentation the survey read defines the codes, so this page does not expand them. A gene id the identity files do not name is kept as the source's own id with no door rather than turned into a symbol.

On citing what a search finds, Reactome says: It should be remembered that while we strive to contain the most current and accurate data, Reactome should not be used in citations where other primary sources of information are available. [R12] The record card prints the literature Reactome attaches to a curated pathway for that reason. The data are public domain: All data in the Reactome database and files derived from that data are licensed under the Creative Commons Public Domain Dedication (CC0). User may copy, modify, and distribute these data, even for commercial purposes, without asking for permission. Attribution is encouraged but not required. [R10] The pathway illustrations are licensed apart, under CC BY 4.0, and none is shown here.

A gene on this list is one Reactome places in this pathway in this release, and that is all the row says: it does not say the gene is expressed in a tissue or associated with a disease, which are the other two explorers' questions, read from other sources. Reactome's papers of record are [R01] [R02].

[R01] Ragueneau E, Gong C, Sinquin P, Sevilla C, Beavers D, Grentner A, et al. (2026). The Reactome Knowledgebase 2026. Nucleic Acids Research 54:D673-D681. PMID 41251150, doi 10.1093/nar/gkaf1223.
[R02] Milacic M, Beavers D, Conley P, Gong C, Gillespie M, Griss J, et al. (2024). The Reactome Pathway Knowledgebase 2024. Nucleic Acids Research 52:D672-D678. PMID 37941124, doi 10.1093/nar/gkad1025.
[R10] Reactome, reactome.org. License Agreement. https://reactome.org/license, read 2026-09-09.
[R12] Reactome, reactome.org. Citing us. https://reactome.org/cite, read 2026-09-09.
[R13] Reactome, reactome.org. Download. https://reactome.org/download-data, read 2026-09-09.

Stable id: R-HSA-9717189.3
Class: Pathway
Species: Homo sapiens (human)
Inferred: no: a curated human pathway
Disease pathway: no
Released: 2021-09-15
Events inside: 3, counted from the record

Taste buds contain at least 3 types of cells: type I cells appear to have a support (glial-like) function; type II cells are responsible for tasting sweet compounds, bitter compounds, and umami (savoury, amino acid) compounds; and type III cells are responsible for tasting sour (acidic) compounds (reviewed in Liman et al. 2014, Roper and Chaudhari 2017, Kinnamon and Finger 2019, Taruno et al. 2021). Recently identified sodium sensing cells expressing the epithelial sodium channel (ENaC) and POU2F3 are thought to be responsible for tasting low concentrations of salt and may be a subset of type II cells or a novel type of taste cell (Chandrashekar et al. 2010, reviewed in Taruno et al. 2021). High concentrations of salt appear to be detected by both type II and type III cells.

Receptors for sweet compounds, bitter compounds, and umami compounds contain an intracellular domain, transmembrane domains, and an extracellular domain that binds the ligand. The extracellular domains of receptors for sweet and umami ligands have a distinctive "venus flytrap"-shaped domain. Upon binding ligand, sweet taste receptors (TAS1R2:TAS1R3 heterodimers), bitter taste receptors (TAS2R class receptors), and umami receptors (TAS1R1:TAS1R3 heterodimers) then signal through a common downstream pathway: the receptor-ligand complex activates an associated heterotrimeric G protein complex (GNAT3:GNB1 or GNB3:GNG13) to exchange GDP for GTP, the heterotrimeric G protein complex dissociates and the resulting GNB1,3:GNG13 complex activates Phospholipase C beta-2 (PLCB2) which hydrolyzes phosphoinositol 4,5-bisphosphate (PI(4,5)P2) to yield inositol 1,4,5-trisphosphate (I(1,4,5)P3) and diacylglycerol (DAG). I(1,4,5)P3 binds and activates ITPR3 to release calcium ions from the endoplasmic reticulum into the cytosol. Cytosolic Ca2+ causes TRPM5 sodium channels to open and depolarize the cell. SCN2A, SCN3A, and SCN9A sodium channels also appear to augment the depolarization. Depolarization causes opening of CALHM1:CALHM3 channels which transport ATP from the cytosol to the extracellular region. ATP then acts as a neurotransmitter in the taste sensing system.

Alternative pathways exist for sensing sugars and glutamate, as evidenced by residual signaling activity in the absence of TAS1R1 or TAS1R3. Glutamate is sensed by the glutamate receptors GRM1 (mGluR1) and GRM4 (mGluR4) expressed in type II taste cells. GRM1 and GRM4 activate calcium channels by an incompletely characterized mechanism that probably involves heterotrimeric G proteins. Glucose may be sensed by a pathway comprising transport into type II taste cells via the glucose transporters SGLT1 and GLUT4, generation of ATP, and inhibition of KATP potassium channels by ATP.

Protons (H+ ions) from acidic compounds translocate from the extracellular region to the cytosol of type III taste cells through the OTOP1 channel. Weak acids such as acetic acid and citric acid are also able to enter type III cells by diffusing through the membrane in their protonated, uncharged forms, Once in the cytosol, the H+ ions inhibit KCNJ2 inwardly rectifying potassium channels, depolarizing the cell. The H+ ions may also open unidentified sodium channels to further depolarize the cell. Depolarization causes exocytosis of the neurotransmitters serotonin (5-HT) and gamma-aminobutyric acid (GABA).

Low concentrations of salt appear to be sensed in specific salt-sensing cells that may be a subset of type II cells. Low concentrations of salt are believed to enter the cell through an epithelial sodium channel (ENaC, SCNN) and the ability to taste low concentrations of salt is dependent on the SCNN1A pore-containing subunit of the SCNN complex in mice. Human taste cells express both SCNN1A and SCNN1D pore-containing subunits. The composition of other subunits of the complex is less certain. The transport of sodium ions (Na+) into the cells depolarizes the plasma membrane and eventually leads to opening of CALHM1:CALHM3 channels which transport ATP from the cytosol to the extracellular region.

Literature Reactome attaches

Taste transduction and channel synapses in taste budsPflugers Arch, 2021, vol. 473, p. 3-13PubMed 32936320
Peripheral coding of tasteNeuron, 2014, vol. 81, p. 984-1000PubMed 24607224
Recent advances in taste transduction and signalingF1000Res, 2019, vol. 8PubMed 32185015
The cells and peripheral representation of sodium taste in miceNature, 2010, vol. 464, p. 297-301PubMed 20107438
Taste buds: cells, signals and synapsesNat Rev Neurosci, 2017, vol. 18, p. 485-497PubMed 28655883

Reactome's record lists 11 orthologous events, R-RNO-9717189 (Rattus norvegicus), R-MMU-9717189 (Mus musculus) among the species this site serves, and 9 in species this site opens no page for.

Reactome ContentService, this pathway's record · Reactome v97 · read 2026-09-30 ET · Reactome pathway browser"Sensory perception of taste". Reactome, release 97, https://reactome.org/PathwayBrowser/#/R-HSA-9717189 with StableID: R-HSA-9717189.3 (accessed 2026-09-30 ET). Reactome version 97 (CC0).

Reading this pathway's record from Reactome (the pathway record).Still reading. A first read of a pathway can take a while; this page waits up to 35 seconds for it, and its scripts then bring in the panel, or a line saying what did not arrive.

02The genes

Genes Reactome places in this human pathway

The mapping files place 47 genes in this human pathway; showing 1 to 47, in pages of 100, sorted by symbol for reading. The order carries no ranking.

Genes Reactome places in this human pathway, page 1 of 1
Gene	Authority id	Mapping file id	Evidence codes
GeneCALHM1	AuthorityHGNC:23494	Mapping file id255022 NCBI file	EvidenceIEA
GeneCALHM3	AuthorityHGNC:23458	Mapping file id119395 NCBI file	EvidenceIEA
GeneGNAT3	AuthorityHGNC:22800	Mapping file id346562 NCBI file	EvidenceIEA, TAS
GeneGNB1	AuthorityHGNC:4396	Mapping file id2782 NCBI file	EvidenceIEA, TAS
GeneGNB3	AuthorityHGNC:4400	Mapping file id2784 NCBI file	EvidenceIEA, TAS
GeneGNG13	AuthorityHGNC:14131	Mapping file id51764 NCBI file	EvidenceIEA, TAS
GeneGRM1	AuthorityHGNC:4593	Mapping file id2911 NCBI file	EvidenceIEA
GeneGRM4	AuthorityHGNC:4596	Mapping file id2914 NCBI file	EvidenceIEA
GeneITPR3	AuthorityHGNC:6182	Mapping file id3710 NCBI file	EvidenceTAS
GeneKCNJ2	AuthorityHGNC:6263	Mapping file id3759 NCBI file	EvidenceIEA
GeneOTOP1	AuthorityHGNC:19656	Mapping file id133060 NCBI file	EvidenceIEA
GenePLCB2	AuthorityHGNC:9055	Mapping file id5330 NCBI file	EvidenceIEA
GeneSCN1B	AuthorityHGNC:10586	Mapping file id6324 NCBI file	EvidenceIEA
GeneSCN2A	AuthorityHGNC:10588	Mapping file id6326 NCBI file	EvidenceIEA
GeneSCN2B	AuthorityHGNC:10589	Mapping file id6327 NCBI file	EvidenceIEA
GeneSCN3A	AuthorityHGNC:10590	Mapping file id6328 NCBI file	EvidenceIEA
GeneSCN4B	AuthorityHGNC:10592	Mapping file id6330 NCBI file	EvidenceIEA
GeneSCN9A	AuthorityHGNC:10597	Mapping file id6335 NCBI file	EvidenceIEA
GeneSCNN1A	AuthorityHGNC:10599	Mapping file id6337 NCBI file	EvidenceTAS
GeneSCNN1B	AuthorityHGNC:10600	Mapping file id6338 NCBI file	EvidenceTAS
GeneSCNN1D	AuthorityHGNC:10601	Mapping file id6339 NCBI file	EvidenceTAS
GeneSCNN1G	AuthorityHGNC:10602	Mapping file id6340 NCBI file	EvidenceTAS
GeneTAS1R1	AuthorityHGNC:14448	Mapping file id80835 NCBI file	EvidenceIEA, TAS
GeneTAS1R2	AuthorityHGNC:14905	Mapping file id80834 NCBI file	EvidenceIEA, TAS
GeneTAS1R3	AuthorityHGNC:15661	Mapping file id83756 NCBI file	EvidenceIEA, TAS
GeneTAS2R1	AuthorityHGNC:14909	Mapping file id50834 NCBI file	EvidenceIEA, TAS
GeneTAS2R10	AuthorityHGNC:14918	Mapping file id50839 NCBI file	EvidenceIEA, TAS
GeneTAS2R13	AuthorityHGNC:14919	Mapping file id50838 NCBI file	EvidenceIEA, TAS
GeneTAS2R14	AuthorityHGNC:14920	Mapping file id50840 NCBI file	EvidenceIEA, TAS
GeneTAS2R16	AuthorityHGNC:14921	Mapping file id50833 NCBI file	EvidenceIEA, TAS
GeneTAS2R20	AuthorityHGNC:19109	Mapping file id259295 NCBI file	EvidenceIEA, TAS
GeneTAS2R3	AuthorityHGNC:14910	Mapping file id50831 NCBI file	EvidenceIEA, TAS
GeneTAS2R30	AuthorityHGNC:19112	Mapping file id259293 NCBI file	EvidenceIEA, TAS
GeneTAS2R31	AuthorityHGNC:19113	Mapping file id259290 NCBI file	EvidenceIEA, TAS
GeneTAS2R38	AuthorityHGNC:9584	Mapping file id5726 NCBI file	EvidenceIEA, TAS
GeneTAS2R39	AuthorityHGNC:18886	Mapping file id259285 NCBI file	EvidenceIEA, TAS
GeneTAS2R4	AuthorityHGNC:14911	Mapping file id50832 NCBI file	EvidenceIEA, TAS
GeneTAS2R40	AuthorityHGNC:18885	Mapping file id259286 NCBI file	EvidenceIEA, TAS
GeneTAS2R41	AuthorityHGNC:18883	Mapping file id259287 NCBI file	EvidenceIEA, TAS
GeneTAS2R43	AuthorityHGNC:18875	Mapping file id259289 NCBI file	EvidenceIEA, TAS
GeneTAS2R46	AuthorityHGNC:18877	Mapping file id259292 NCBI file	EvidenceIEA, TAS
GeneTAS2R5	AuthorityHGNC:14912	Mapping file id54429 NCBI file	EvidenceIEA, TAS
GeneTAS2R50	AuthorityHGNC:18882	Mapping file id259296 NCBI file	EvidenceIEA, TAS
GeneTAS2R7	AuthorityHGNC:14913	Mapping file id50837 NCBI file	EvidenceIEA, TAS
GeneTAS2R8	AuthorityHGNC:14915	Mapping file id50836 NCBI file	EvidenceIEA, TAS
GeneTRPM4	AuthorityHGNC:17993	Mapping file id54795 NCBI file	EvidenceIEA
GeneTRPM5	AuthorityHGNC:14323	Mapping file id29850 NCBI file	EvidenceIEA

Evidence codes on this page: IEA, TAS, as the mapping file writes them; a row carrying two was written twice by the file, once under each. The mapping file id says which file placed the gene: an NCBI Gene id from NCBI2Reactome_All_Levels.txt, an Ensembl gene id from Ensembl2Reactome_All_Levels.txt. The two files can disagree about a code, so a row's codes are the one file's view. Measured by this site's build over this release on 2026-09-09: of the 138,908 human pathway-gene pairs both files place, 207 (0.149 per cent, over 47 genes) carry TAS in the Ensembl file where the NCBI rows carry IEA alone.

Reactome mapping files, the human rows for this pathway · Reactome release 97 · read 2026-09-09 · Reactome downloads"NCBI2Reactome_All_Levels.txt" and "Ensembl2Reactome_All_Levels.txt", Reactome, release 97, https://reactome.org/download-data/ (date of access 2026-09-09). Data CC0; attribution encouraged.

03The hierarchy

Parents and children in this release's hierarchy

Parents

Sensory PerceptionR-HSA-9709957641 genes

Children

Reactome's hierarchy is a graph rather than a tree: a pathway can sit under more than one parent, and the gene counts are each pathway's own placements at every level under it, so a parent's count is not the sum of its children's.

Reactome, the human pathway list and hierarchy relationship file · Reactome release 97 · read 2026-09-09 · Reactome downloads"ReactomePathways.txt" and "ReactomePathwaysRelation.txt", Reactome, release 97, https://reactome.org/download-data/ (date of access 2026-09-09). Data CC0; attribution encouraged.