The ability to taste gives animals a means to assess the identity and quality of potential food substances. In an Advanced Online Publication from Nature, Greg Nelson and colleagues at the University of California at San Diego describe characterization of the mammalian amino-acid taste receptor (Nature 2002, DOI 10.1038/nature726).

They employed an expression screening strategy, expressing putative G-protein-coupled receptors in human cells and assaying for stimulus-induced changes in intracellular calcium. A combination of mouse T1R1 and T1R3 taste receptors generated an effective heteromeric receptor for the 20 standard L-amino acids, but not D-amino acids. Amino acids can represent both sweet and unami ('delicious') tastes.

Nelson et al. also demonstrated that species-specific sequence differences in T1R taste receptors affect taste perception.