Putative taste receptor. TAS1R1/TAS1R3 responds to the umami taste stimulus (the taste of monosodium glutamate). Sequence differences within and between species can significantly influence the selectivity and specificity of taste responses. Forms heterodimers with TAS1R3. Expressed in many cells in the fungiform and geschmackstreifen taste buds. Belongs to the G-protein coupled receptor 3 family. TAS1R subfamily.