The TAS2Rs are family of G Proteins for flavour preferences in plants.

 A family of G proteins plants.

The sense of bitterness is essential to animal behavior and fitness. It allows animals to avoid exposure by alerting them to the presence of poisons in food, especially unpleasant defensive chemicals contained in plants. TAS2Rs are a class of G protein-coupled receptors expressed on the surface of taste buds that in vertebrates mediate bitter perception. 

They keep an eye on the contents of foods, beverages, and other substances as they are consumed there, with their orientation toward the inside of the mouth. TAS2Rs react to bitter substances by initiating neuronal pathways that result in feeling. 

Because of this significance, TAS2Rs have been subject to selective pressures across their evolutionary history, which has left its mark on patterns of gene acquisition and loss, sequence polymorphism, and population structure that are in line with the various eating ecologies of vertebrates.