Home About us Activities Products Articles Clients Photo Albums Links  

Sweet tastants stimulate

Sweet tastants stimulate adenylate cyclase coupled to GTP-binding protein in rat tongue membranes


Benjamin J. STRIEM,1 Umberto PACE,2 Uri ZEHAVI,1 Michael NAIM1* and Doron LANCET2
1 Department of Biochemistry and Human Nutrition, Faculty of Agriculture, The Hebrew University of Jerusalem,
Rehovot 76100
2 Department of Membrane Research, The Weizmann Institute of Science, Rehovot 76100, Israel
* To whom correspondence and reprint requests should be sent.

Biochem. J. (1989) 260, 121-126 (Printed in Great Britain)

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.

Abbreviations used: AMP-Adenosine-Mono-Phospate, G-protein, GTP- or guanine-nucleotide-binding protein; GTP[S], guanosine 5'-[y-thiojtriphosphate; ATTE, anterior tongue taste epithelium; TM, tongue muscle; TNSE, tongue non-sensory epithelium; SM, skeletal muscle; OC, olfactory cilia; G., stimulatory-type G-protein; NHD, neohesperidin dihydrochalcone.

 To List of Articles









Print  |   Send to a friend  |   Add to favorites

Home |  Dr. Benjamin Striem  |  Activities  |  Products |  Articles |  Clients |  Album |  Links |  Terms
POB 1300 Rehovot 76115 • Tel. +972-8-9450815 • Mobile: +972-50-7632337 • Fax: +972-8-9494231. • benjamin@striem.com
Built by Indigo Design and Websites   |  © all rights reserved