title: Sweet tastants stimulate adenylate cyclase coupled to GTP-binding protein in rat tongue membranes.
abstract: Sucrose and other saccharides, which produce an appealing taste in rats, were found to significantly stimulate the activity of adenylate cyclase in membranes derived from the anterior-dorsal region of rat tongue. In control membranes derived from either tongue muscle or tongue non-sensory epithelium, the effect of sugars on adenylate cyclase activity was either much smaller or absent. Sucrose enhanced adenylate cyclase activity in a dose-related manner, and this activation was dependent on the presence of guanine nucleotides, suggesting the involvement of a GTP-binding protein ('G-protein'). The activation of adenylate cyclase by various mono- and di-saccharides correlated with their electrophysiological potency. Among non-sugar sweeteners, sodium saccharin activated the enzyme, whereas aspartame and neohesperidin dihydrochalcone did not, in correlation with their sweet-taste effectiveness in the rat. Sucrose activation of the enzyme was partly inhibited by Cu2+ and Zn2+, in agreement with their effect on electrophysiological sweet-taste responses. Our results are consistent with a sweet-taste transduction mechanism involving specific receptors, a guanine-nucleotide-binding protein and the cyclic AMP-generating enzyme adenylate cyclase.
authors.affiliation: Department of Biochemistry and Human Nutrition, Faculty of Agriculture, Hebrew University of Jerusalem, Rehovo, Israel.
authors.forename: B J
authors.initials: BJ
authors.lastname: Striem
authors.forename: U
authors.initials: U
authors.lastname: Pace
authors.forename: U
authors.initials: U
authors.lastname: Zehavi
authors.forename: M
authors.initials: M
authors.lastname: Naim
authors.forename: D
authors.initials: D
authors.lastname: Lancet
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D004187:Disaccharides / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D019204:GTP-Binding Proteins / Q000502:physiology*; D008297:Male; D009005:Monosaccharides / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D015398:Signal Transduction; D013395:Sucrose / Q000494:pharmacology; D013549:Sweetening Agents / Q000494:pharmacology; D013650:Taste Buds / Q000187:drug effects / Q000201:enzymology*
chemical_list: D004187:Disaccharides; D009005:Monosaccharides; D013549:Sweetening Agents; D013395:Sucrose; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases