Transduction of bitter and sweet taste by gustducin.
Several lines of evidence suggest that both sweet and bitter tastes are transduced via receptors coupled to heterotrimeric guanine-nucleotide-binding proteins (G proteins). Gustducin is a taste receptor cell (TRC)-specific G protein that is closely related to the transducins. Gustducin and rod transducin, which is also expressed in TRCs, have been proposed to couple bitter-responsive receptors to TRC-specific phosphodiesterases to regulate intracellular cyclic nucleotides. Here we investigate gustducin's role in taste transduction by generating and characterizing mice deficient in the gustducin alpha-subunit (alpha-gustducin). As predicted, the mutant mice showed reduced behavioural and electrophysiological responses to bitter compounds, whereas they were indistinguishable from wild-type controls in their responses to salty and sour stimuli. Unexpectedly, mutant mice also exhibited reduced behavioural and electrophysiological responses to sweet compounds. Our results suggest that gustducin is a principal mediator of both bitter and sweet signal transduction.
Wong
G T
GT
Department of Physiology and Biophysics, Mount Sinai School of Medicine, New York 10029, USA.
Gannon
K S
KS
Margolskee
R F
RF
D000818:Animals; D003001:Cloning, Molecular; D005154:Facial Nerve / Q000502:physiology; D005260:Female; D006146:Guanidines; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D016296:Mutagenesis; D000644:Quaternary Ammonium Compounds; D011803:Quinine; D015398:Signal Transduction; D012965:Sodium Chloride; D013395:Sucrose; D013549:Sweetening Agents; D013649:Taste / Q000235:genetics / Q000502:physiology*; D013650:Taste Buds / Q000502:physiology; D015293:Transducin / Q000172:deficiency / Q000235:genetics / Q000502:physiology*
D006146:Guanidines; D000644:Quaternary Ammonium Compounds; D011803:Quinine; D012965:Sodium Chloride; D013395:Sucrose; D013549:Sweetening Agents; D015293:Transducin; C099860:SC 45647; C075192:gustducin; C043414:denatonium