Taste receptor type 2 member 1 (TAS2R1/T2R1) is a protein that in humans is encoded by the TAS2R1gene.[5][6][7] 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.[8] 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.[9]
Expression and function
Extra-oral roles of TAS2Rs
Bitter taste receptors are expressed in taste receptor cells, which organized into taste buds on the papillae of the tongue and palate epithelium.
In addition, TAS2Rs were found to be expressed in extra-oral tissues, e.g. brain, lungs, gastrointestinal tract, etc.[9] So far, less is known about their function however, for example it was shown that:
TAS2Rs mediate relaxation of airway smooth muscles.[10]
TAS2R43 is involved in secretion of gastric acid in the stomach.[11]
Extra-oral roles of TAS2R1
TAS2R1, TAS2R4, TAS2R10, TAS2R38 and TAS2R49 were found to be down-regulated in breast cancer cells[12].
TAS2R1, causes vasoconstrictor responses in the pulmonary circuit and relaxation in the airways[13].
Numbering is according to the Balleros-Weinstein[16] system.
Unlike in Class A GPCRs, in transmembrane helix 4 no DRY[17] motif was found as well as position 6.50 is not conserved.
TAS2R1 gene
This gene encodes a member of a family of candidate taste receptors that are members of the G protein-coupled receptor superfamily and that are specifically expressed by taste receptor cells of the tongue and palate epithelia. This intronless taste receptor gene encodes a 7-transmembrane receptor protein, functioning as a bitter taste receptor.
SNPs
In T2R1 two SNPs are known in R111H and R206W (dbSNP).
Transcription factors
So far, AML1a, AP-1, AREB6, FOXL1, IRF-7A, Lmo2, NF-E2, NF-E2 p45 were found as the top transcription factor binding sites by QIAGEN in the TAS2R1 gene promoter.
^ abDi Pizio A, Levit A, Slutzki M, Behrens M, Karaman R, Niv MY (2016), "Comparing Class a GPCRS to bitter taste receptors", G Protein-Coupled Receptors - Signaling, Trafficking and Regulation, Methods in Cell Biology, vol. 132, Elsevier, pp. 401–427, doi:10.1016/bs.mcb.2015.10.005, ISBN978-0-12-803595-5, PMID26928553
^Singh N, Chakraborty R, Bhullar RP, Chelikani P (April 2014). "Differential expression of bitter taste receptors in non-cancerous breast epithelial and breast cancer cells". Biochemical and Biophysical Research Communications. 446 (2): 499–503. doi:10.1016/j.bbrc.2014.02.140. ISSN0006-291X. PMID24613843.
^Ballesteros JA, Weinstein H (1995), "[19] Integrated methods for the construction of three-dimensional models and computational probing of structure-function relations in G protein-coupled receptors", Methods in Neurosciences, Elsevier, pp. 366–428, doi:10.1016/s1043-9471(05)80049-7, ISBN978-0-12-185295-5