Variants of 'umami' taste receptor contribute to our individualized flavor worlds

July 8, 2009

Using a combination of sensory, genetic, and in vitro approaches, researchers from the Monell Center confirm that the T1R1-T1R3 taste receptor plays a role in human umami (amino acid) taste.

They further report that variations in the genes that code for this receptor correspond to individual variation in sensitivity to and perceived intensity of umami .

"These findings bolster our understanding of human taste variation and individual differences in tastes for essential nutrients," says senior author Paul A.S. Breslin PhD, a sensory geneticist at Monell.

Umami is the taste quality associated with several , especially the amino acid L-glutamate. High levels of glutamate are present in many protein-rich foods, including meats and cheeses, in vegetables such as mushrooms, peas, and tomatoes, and in human breast milk.

Amino acids are the building blocks of protein, an essential macronutrient.

Commenting on clinical implications of the work, Breslin says, "Protein-energy malnutrition is one of the leading causes of death in children worldwide. Increased understanding of amino acid taste receptors may help nutritionists target the appetites of protein-malnourished children to provide good-tasting dietary supplements that kids will readily accept."

The findings, published online in the , strengthen the claim that umami is a fundamental human taste quality -- similar to sweet, salty, bitter and sour -- that indicates the presence of amino acids, peptides and related structures.

In the study, Breslin and his team first conducted sensory tests on 242 individuals, who were asked to discriminate the taste of weak L-glutamate from salt. Approximately 5% were unable to tell the two tastes apart, indicating that certain people are highly insensitive to umami and thus have difficulty detecting low levels of this taste quality.

An additional 87 individuals were asked to assess the intensity of glutamate's umami taste. The subjects tasted five concentrations of glutamate and rated the umami intensity of each on a scale that ranged from 'no sensation' to 'the strongest imaginable.'

The researchers next examined DNA from these 87 individuals to look for variations in the genes that code for T1R1 and T1R3, two protein subunits that combine to form the G-protein coupled receptor T1R1-T1R3. Comparing DNA structure to the glutamate taste responses of each individual, they found that variations (known as SNPs; single nucleotide polymorphisms) at three sites on the T1R3 gene were associated with increased sensitivity to glutamate taste.

A fourth set of studies used in vitro cell biology techniques to provide additional evidence that T1R1-T1R3 is a human amino acid taste receptor. When human T1R1-T1R3 receptors were expressed in a host cell line, these cells were able to respond specifically to L-glutamate.

Together, the findings demonstrate that the T1R1-T1R3 receptor significantly affects human sensitivity to umami taste from glutamate, and that individual differences in umami perception are due, at least in part, to coding variations in the T1R3 gene.

"We want to further understand the degree to which these genes account for umami taste perception," said Breslin. "This will in turn help in the discovery of other taste receptors that may play a role in umami taste and aid in our understanding of appetites."

He also speculates that because these same receptors are also found in the gastrointestinal tract, liver and pancreas, coding variation in the T1R3 gene may also influence how proteins and amino acids are processed metabolically.

Source: Monell Chemical Senses Center (news : web)

Related Stories

Recommended for you

Hibernating ground squirrels provide clues to new stroke treatments

November 17, 2017
In the fight against brain damage caused by stroke, researchers have turned to an unlikely source of inspiration: hibernating ground squirrels.

Age and gut bacteria contribute to multiple sclerosis disease progression

November 17, 2017
Researchers at Rutgers Robert Wood Johnson Medical School published a study suggesting that gut bacteria at young age can contribute to multiple sclerosis (MS) disease onset and progression.

Molecular guardian defends cells, organs against excess cholesterol

November 16, 2017
A team of researchers at the Harvard T. H. Chan School of Public Health has illuminated a critical player in cholesterol metabolism that acts as a molecular guardian in cells to help maintain cholesterol levels within a safe, ...

Prototype ear plug sensor could improve monitoring of vital signs

November 16, 2017
Scientists have developed a sensor that fits in the ear, with the aim of monitoring the heart, brain and lungs functions for health and fitness.

Ancient enzyme could boost power of liquid biopsies to detect and profile cancers

November 16, 2017
Scientists are developing a set of medical tests called liquid biopsies that can rapidly detect the presence of cancers, infectious diseases and other conditions from only a small blood sample. Researchers at The University ...

FDA to crack down on risky stem cell offerings

November 16, 2017
U.S. health authorities announced plans Thursday to crack down on doctors pushing stem cell procedures that pose the gravest risks to patients amid an effort to police a burgeoning medical field that previously has received ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.