Gustducin and its role in taste.
The mechanisms responsible for taste signal transductions are very complex. A key molecule, alpha-gustducin, a primarily taste-specific G protein alpha-subunit, was discovered in 1992 and was later found to be involved in both bitter and sweet taste transduction. A proposed mechanism for alpha-gustducin involves coupling specific cell-surface receptors with a cyclic nucleotide phosphodiesterase which would open a cyclic nucleotide-suppressible cation channel leading to influx of calcium, and ultimately leading to release of neurotransmitter. Although "knock-out" animals deficient in the alpha-gustducin gene clearly demonstrate that gustducin is an essential molecule for tasting certain bitter and sweet compounds, the precise role of alpha-gustducin in bitter and sweet taste is presently unclear. Indeed, there are several other signaling mechanisms in sweet and bitter taste, apparently unrelated to alpha-gustducin, that increase cyclic AMP or inositol 1,4,5 trisphosphate. Thus, proposed models for alpha-gustducin and those found by other laboratories may be parallel and interdependent.
Spielman
A I
AI
New York University College of Dentistry, Basic Science Division, New York 10010, USA.
D000818:Animals; D015220:Calcium Channels / Q000502:physiology; D000242:Cyclic AMP / Q000502:physiology; D019204:GTP-Binding Proteins / Q000145:classification; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000502:physiology; D018377:Neurotransmitter Agents / Q000502:physiology; D009711:Nucleotides / Q000502:physiology; D010727:Phosphoric Diester Hydrolases / Q000502:physiology; D011956:Receptors, Cell Surface / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology; D013649:Taste / Q000502:physiology*; D015293:Transducin / Q000235:genetics / Q000502:physiology*
D015220:Calcium Channels; D018377:Neurotransmitter Agents; D009711:Nucleotides; D011956:Receptors, Cell Surface; C075192:gustducin; D015544:Inositol 1,4,5-Trisphosphate; D000242:Cyclic AMP; D010727:Phosphoric Diester Hydrolases; D019204:GTP-Binding Proteins; D015293:Transducin