The mammalian sense of taste, a crucial natural mechanism for the evaluation of healthy food and recognition of toxic substances, is the result of a complex, multiscale signal transduction process. From the molecular/subcellular point of view, taste receptors are highly specialized proteins that allow the activation or deactivation of signalling pathways and the consequent perception of the five basic tastes: sweet, umami, bitter, salty and sour. Among them, the bitter taste is the one developed by nature to allow screening food molecules against poisons. A number of 25 different human bitter taste receptors (TS2R) has been identified till now. However, our knowledge of bitter taste mechanisms is limited by a lack of experimental data concerning the above-mentioned machinery structural features.