The complex of G proteins has been named gustducin because of its similarity in structure and action to the transducin that plays such an essential role in rod vision.（G protein的複合體叫味蛋白，也就是味轉導素）Activation of gustducin triggers a cascade of intracellular reactions:production of the second messengers inositol trisphosphate (IP3) and diacylglycerol (DAG) which當味蛋白被啟用後，會生產三磷酸肌醇和二醯甘油releases intracellular stores of Ca++ which釋放原本儲存的鈣離子allows in the influx of Na+ ions depolarizing the cell and causing the因此鈉離子會將細胞去極，使release of ATP, which三磷酸腺甙被釋放triggers action potentials in a nearby sensory neuron.刺激附近的感覺神經元所以，不是糖是我們感覺到甜，而是說一切含有可以和GPCR結合的分子或離子的食物都可以使我們感覺到甜。Reference：The Sense of Taste
準確的說，我們感覺到甜是因為我們所吃下的東西中的分子或離子與口腔中的G-protein-coupled receptors (GPCRs) 結合，裡面的化學元素T1R2和T1R3聯對（couple）成為G proteins。然後後面還有好長一串反應：
The complex of G proteins has been named gustducin because of its similarity in structure and action to the transducin that plays such an essential role in rod vision.（G protein的複合體叫味蛋白，也就是味轉導素）Activation of gustducin triggers a cascade of intracellular reactions:production of the second messengers inositol trisphosphate (IP3) and diacylglycerol (DAG) which當味蛋白被啟用後，會生產三磷酸肌醇和二醯甘油releases intracellular stores of Ca++ which釋放原本儲存的鈣離子allows in the influx of Na+ ions depolarizing the cell and causing the因此鈉離子會將細胞去極，使release of ATP, which三磷酸腺甙被釋放triggers action potentials in a nearby sensory neuron.刺激附近的感覺神經元所以，不是糖是我們感覺到甜，而是說一切含有可以和GPCR結合的分子或離子的食物都可以使我們感覺到甜。Reference：The Sense of Taste