Ming D, Ninomiya Y, Margolskee R F
Department of Physiology and Biophysics, The Mount Sinai School of Medicine, Box 1677, One Gustave L. Levy Place, New York, NY 10029, USA.
Proc Natl Acad Sci U S A. 1999 Aug 17;96(17):9903-8. doi: 10.1073/pnas.96.17.9903.
Gustducin, a transducin-like guanine nucleotide-binding regulatory protein (G protein), and transducin are expressed in taste receptor cells where they are thought to mediate taste transduction. Gustducin and transducin are activated in the presence of bovine taste membranes by several compounds that humans perceive to be bitter. We have monitored this activation with an in vitro assay to identify compounds that inhibited taste receptor activation of transducin by bitter tastants: AMP and chemically related compounds inhibited in vitro responses to several bitter compounds (e.g., denatonium, quinine, strychnine, and atropine). AMP also inhibited behavioral and electrophysiological responses of mice to bitter tastants, but not to NaCl, HCl, or sucrose. GMP, although chemically similar to AMP, inhibited neither the bitter-responsive taste receptor activation of transducin nor the gustatory responses of mice to bitter compounds. AMP and certain related compounds may bind to bitter-responsive taste receptors or interfere with receptor-G protein coupling to serve as naturally occurring taste modifiers.
味觉传导素是一种与转导素类似的鸟嘌呤核苷酸结合调节蛋白（G蛋白），转导素在味觉受体细胞中表达，人们认为它们在其中介导味觉转导。在牛味觉膜存在的情况下，几种被人类感知为苦味的化合物可激活味觉传导素和转导素。我们通过体外试验监测这种激活情况，以鉴定抑制苦味剂对转导素味觉受体激活的化合物：AMP及化学相关化合物抑制了对几种苦味化合物（如苯甲地那铵、奎宁、士的宁和阿托品）的体外反应。AMP还抑制了小鼠对苦味剂的行为和电生理反应，但对NaCl、HCl或蔗糖无抑制作用。GMP虽然在化学结构上与AMP相似，但既不抑制苦味反应性味觉受体对转导素的激活，也不抑制小鼠对苦味化合物的味觉反应。AMP和某些相关化合物可能与苦味反应性味觉受体结合，或干扰受体与G蛋白的偶联，从而作为天然存在的味觉调节剂。
