A study published in the February 22 issue of Current Biology confirms the influential role of genetics in determining the wide range of human sensitivity to taste, ultimately impacting how we each perceive the world in a slightly different way.
"Each human carries their own distinctive set of taste receptors which gives them a unique perception of how foods and medicines taste," explains Monell Chemical Senses Center psychophysicist Paul Breslin, PhD, who shares first authorship and is a corresponding contributor for the study. "This paper shows that a single gene codes for multiple forms of a taste receptor, with each form having a differing sensitivity to taste compounds. Further, a person's perceptual sensitivity to these bitter tasting compounds corresponds strikingly well with their genetically-determined receptor sensitivity."
In the paper, researchers at the Monell Center and collaborating institutions related individual perception of the bitter-tasting compounds PTC and PROP to variation in a bitter taste receptor gene known as hTAS2R38.
The researchers cloned two forms (haplotypes) of the hTAS2R38 gene and expressed the corresponding receptors in a cell culture. The two haplotypes, known as PAV and AVI, vary with respect to amino acid substitutions encoded at certain positions on the taste receptor protein.
In the cell culture experiments, small amounts of the bitter compounds activated cells expressing the PAV form of the receptor, whereas cells expressing the AVI form were unresponsive to the same compounds. Cells expressing other haplotypes (eg PVI, AAI or AAV) had intermediate sensitivity to the bitter compounds.
Other experiments examined bitterness perception in human subjects. People with the PAV form of the hTAS2R38 gene were most sensitive to the bitter taste of PROP a
Contact: Paul Breslin
Monell Chemical Senses Center