TAS1R1 is a G protein-coupled taste receptor that functions as the primary umami taste detector when heterodimerized with TAS1R3 1. The TAS1R1/TAS1R3 heterodimer responds to monosodium glutamate (MSG) and related glutamate compounds through ligand-binding domains in the extracellular N-terminal region 2. TAS1R1 is predominantly expressed in fungiform papillae taste buds, with expression confirmed through immunohistochemistry and RT-PCR in all tested subjects, including those with specific ageusia for glutamate 13. Genetic variation significantly influences umami taste sensitivity. Multiple nonsynonymous single nucleotide polymorphisms (nsSNPs) in TAS1R1, including C329T and G1114A, associate with inter-individual differences in glutamate detection sensitivity 1. TAS1R1 polymorphisms also correlate with broader taste intensity perception across multiple taste qualities and influence food choices, particularly fat and calorie consumption 45. Beyond taste, TAS1R3 (the obligate heterodimeric partner) functions in extraoral tissues. TAS1R3 homodimers in osteoclasts detect glucose and regulate bone resorption independently of umami taste function 6. Additionally, mGlu2/TAS1R3 heteromers in immune cells detect MSG and modulate neutrophil responses 7. These findings reveal TAS1R1's fundamental role in umami perception while highlighting broader physiological functions of the TAS1R family in metabolism and immunity.