Taste Transduction
Description: All taste pathways are proposed to converge on common elements that mediate a rise in intracellular Ca2+ followed by neurotransmitter release. Na+ salt depolarizes taste cells by passive influx of Na+ through the amiloride-sensitive Na+ channel (ENaC). Acids depolarize taste cells by a variety of mechanisms, including influx of protons (H+) through ENaC and a proton-gated cation channel (MDEG). Two putative umami receptors have been identified: a truncated variant of the metabotropic glutamate receptor mGluR4 and the heterodimer, T1R1 + T1R3. Umami receptors are coupled to a signaling pathway involving activation of PLCbeta2, production of IP3 and diacylglycerol, release of Ca2+ from intracellular stores and activation of a transient receptor potential channel, TRPM5. Bitter compounds, such as denatonium and PROP, activate particular T2R/TRB isoforms, which activate gustducin heterotrimers. Activated alpha-gustducin stimulates PDE to hydrolyze cAMP, whereas betagamma subunits activate PLCbeta2 to generate IP3, which leads to release of Ca2+ from internal stores. Artificial sweeteners activate GPCRs (T1R heterodimers) apparently linked via PLC to IP3 production and release of Ca2+ from intracellular stores. Sugars apparently activate GPCRs linked via AC to cAMP production which, in turn, may inhibit basolateral K+ channels through phosphorylation by cAMP-activated protein kinase A (PKA). Source: KEGG (hsa04742)
Related BMRB Molecules
- cAMP
- D-Fructose
- D-Galactose
- D-Glucose
- L-Glutamic Acid
- Inosine-5'-monophosphate
- Lactose
- D-Maltose
- D-Mannose
- D-Sorbose
- Sucrose
For complete information about pathway, see KEGG [map04742]