Nav: Home

Gaining a better understanding of the way we taste

July 20, 2016

For the first time Japanese researchers discovered that the extracellular domain of taste receptor proteins undergoes a change in structure by binding together taste substances. This structure change is thought to transmit the extracellular binding of taste substances to taste cells. The findings will contribute to our basic understanding of taste mechanisms and the development of a new taste evaluation system that makes use of the screening and detection of taste receptor structure changes.

Our sense of taste enables us to recognize the chemical substances in food and form judgments as to whether these include nutrients that are necessary for our survival or poisonous substances that would cause us harm. For each of the five basic tastes of sweet, umami, salty, sour and bitter, we possess respective sensor protein taste receptors. In the fields of molecular biology and biochemistry it has become possible to produce a variety of biological proteins using cells in experimental settings. However, producing a greater quantity of taste receptors and maintaining their proper structure and function in lab settings has so far been unsuccessful. This has prevented their precise analysis resulting in a lack of understanding of the detailed processes of taste substance binding and related processes.

A group of researchers led by Atsuko Yamashita, Professor at the Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Eriko Nango, Researcher at the RIKEN SPring-8 Center, Yuji Ashikawa, at the time Researcher at the RIKEN SPring-8 Center, Saori Maki, Researcher at the RIKEN SPring-8 Center, Shuji Akiyama, Professor at Institute for Molecular Science, National Institute of Natural Sciences, Yuko Kusakabe, Unit Leader at the Food Research Institute, National Agriculture and Food Research Organization, and Susumu Uchiyama, Assistant Professor at the Graduate School of Engineering, Osaka University now made the discovery that the extracellular domain of taste receptor proteins changes when taste substances bind together.

In their study, the researchers were able to produce extracellular domains of T1r2 and T1r3 heterodimer taste receptors of Medaka fish using cultured insect cells. The so-called T1r (Taste receptor type 1) family consists of proteins that serve as taste receptors recognizing sweet tastes and glutamine acid (umami taste). These receptors are located in the extracellular domain, the transmembrane, which is embedded in the cell membrane, and the intracellular domain. They achieve their function as sweet and umami receptors by forming heterodimers (a state in which two different types of proteins are grouped together). Since two thirds of the T1r family receptors protrude from taste cells and therefore are exposed within the mouth, this extracellular domain is considered to be the main binding region for taste substances. In other words, taste perception starts in this extracellular domain where taste substances bind together. In the study, the researchers clarified that the extracellular domain structure of taste receptor protein changes into a compact state as taste substances bind together. They also made the finding that this structure change is based on the reciprocal influence of the protein molecules that make up heterodimers. Based on their study findings, the researchers inferred that information on taste substance binding taking place outside of the cell is transmitted to the remaining one third of receptors located in the transmembrane and the intracellular domain via this structure change.

The research results represent a major step towards conducting precise analyses using purified protein samples produced in the laboratory. In addition, a system evaluating the binding of taste substances by detecting the structure change of taste receptors was created (patent application 2013-246300). If the production of human taste receptors becomes possible, this can lead to the development of an evaluation system for taste substances capable of discerning what humans perceive as palatable.

This research was featured in the British Scientific Journal Scientific Reports on May 10th, 2016 (British Time).

Osaka University

Related Proteins Articles:

Coupled proteins
Researchers from Heidelberg University and Sendai University in Japan used new biotechnological methods to study how human cells react to and further process external signals.
Understanding the power of honey through its proteins
Honey is a culinary staple that can be found in kitchens around the world.
How proteins become embedded in a cell membrane
Many proteins with important biological functions are embedded in a biomembrane in the cells of humans and other living organisms.
Finding the proteins that unpack DNA
A new method allows researchers to systematically identify specialized proteins called 'nuclesome displacing factors' that unpack DNA inside the nucleus of a cell, making the usually dense DNA more accessible for gene expression and other functions.
A brewer's tale of proteins and beer
The transformation of barley grains into beer is an old story, typically starring water, yeast and hops.
New tool for the crystallization of proteins
ETH researchers have developed a new method of crystallizing large membrane proteins in order to determine their structure.
New interaction mechanism of proteins discovered
UZH researchers have discovered a previously unknown way in which proteins interact with one another and cells organize themselves.
When proteins shake hands
Protein nanofibres often have outstanding properties such as a high stability, biodegradability, or antibacterial effect.
Proteins' fluorescence a little less mysterious
Rice University scientists use simulations to understand the mechanism behind a popular fluorescent protein used to monitor signals between neurons.
New study suggests health benefits of swapping animal proteins for plant proteins
Substituting one to two servings of animal proteins with plant proteins every day could lead to a small reduction in the three main cholesterol markers for cardiovascular disease prevention, a new study suggests.
More Proteins News and Proteins Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

Why do we revere risk-takers, even when their actions terrify us? Why are some better at taking risks than others? This hour, TED speakers explore the alluring, dangerous, and calculated sides of risk. Guests include professional rock climber Alex Honnold, economist Mariana Mazzucato, psychology researcher Kashfia Rahman, structural engineer and bridge designer Ian Firth, and risk intelligence expert Dylan Evans.
Now Playing: Science for the People

#541 Wayfinding
These days when we want to know where we are or how to get where we want to go, most of us will pull out a smart phone with a built-in GPS and map app. Some of us old timers might still use an old school paper map from time to time. But we didn't always used to lean so heavily on maps and technology, and in some remote places of the world some people still navigate and wayfind their way without the aid of these tools... and in some cases do better without them. This week, host Rachelle Saunders...
Now Playing: Radiolab

Dolly Parton's America: Neon Moss
Today on Radiolab, we're bringing you the fourth episode of Jad's special series, Dolly Parton's America. In this episode, Jad goes back up the mountain to visit Dolly's actual Tennessee mountain home, where she tells stories about her first trips out of the holler. Back on the mountaintop, standing under the rain by the Little Pigeon River, the trip triggers memories of Jad's first visit to his father's childhood home, and opens the gateway to dizzying stories of music and migration. Support Radiolab today at