Wong G T, Gannon K S, Margolskee R F
Department of Physiology and Biophysics, Mount Sinai School of Medicine, New York 10029, USA.
Nature. 1996 Jun 27;381(6585):796-800. doi: 10.1038/381796a0.
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.
多条证据表明，甜味和苦味都是通过与异源三聚体鸟嘌呤核苷酸结合蛋白（G蛋白）偶联的受体进行转导的。味导素是一种味觉受体细胞（TRC）特异性G蛋白，与转导素密切相关。味导素和也在TRC中表达的视杆转导素，被认为可将苦味反应性受体与TRC特异性磷酸二酯酶偶联，以调节细胞内环核苷酸。在这里，我们通过生成并鉴定味导素α亚基（α-味导素）缺陷的小鼠，来研究味导素在味觉转导中的作用。正如所预测的，突变小鼠对苦味化合物的行为和电生理反应减弱，而它们对咸味和酸味刺激的反应与野生型对照没有区别。出乎意料的是，突变小鼠对甜味化合物的行为和电生理反应也减弱。我们的结果表明，味导素是苦味和甜味信号转导的主要介质。
