|The advance online edition of the Nature journal states that scientists have identified the receptor we use to taste amino acids, the building blocks of proteins. "The receptor, T1R1+3, seems to be involved with umami, the savory taste of meats and other foods that are rich in amino acids called glutamates."
Recently, a mGluR4 splice variant has been reported as a candidate umami receptor. The authors say their results demonstrate that T1R1 and T1R3 combine to function as a broadly tuned amino-acid receptor.
Nelson,G., Chandrashekar,J., Hoon,M., Feng,L., Zhao,G., Ryba,N. and Zuker,C.Nature advance online publication, 24 February 2002 (DOI 10.1038/nature726)