Over the past few years, taste researchers have identified various molecules on the tongue that respond to bitter and sweet substances. They've now found another so-called taste receptor, one that responds to almost all of the 20 amino acids that make up proteins.
The new receptor may help explain why people so savor the flavor, called umami, that is typical of cheese, meat, and other glutamate-rich food. When added to a meal, monosodium glutamate, or MSG, elicits this taste, as well.
The amino acid taste-receptor actually uses two previously discovered taste receptor proteins as its subunits, the scientists report in the March 14 Nature. Both the human and mouse versions of this receptor respond to a broad range of amino acids, albeit with different sensitivities to some.
"For a mouse, it's possible that MSG elicits the same perceptual response as other amino acids," notes study coauthor Charles S. Zuker, a Howard Hughes Medical Institute investigator at