When you step out on a frosty morning or pop a mint into your mouth, you instantly feel a cool rush. That feeling starts with a tiny sensor inside your skin that tells your brain something is cold.
Researchers have now taken the first clear pictures of this sensor. The work was shown at a big science meeting in San Francisco.
The sensor is a protein called TRPM8. Think of TRPM8 as a microscopic thermometer that lives in the nerves of your skin, mouth, and eyes. When the temperature drops to about 8‑28 °C (46‑82 °F), the protein opens a tiny gate. Ions flow through the gate, sending a signal to the brain that we feel as cold.
Menthol, the chemical that makes mint taste cool, tricks the same gate. It sticks to a special spot on TRPM8 and forces the gate open, even though the temperature hasn't changed. So menthol creates the same brain signal as real cold.
Cryo‑electron microscopy shows the gate moving
To see the gate in action, scientists froze the protein and shot it with electrons. The pictures showed TRPM8 changing shape from a closed to an open form.
Cold and menthol open the gate in slightly different ways. Cold mainly reshapes the pore part of the protein. Menthol binds elsewhere, pulls the protein, and then the shape change spreads to the pore, opening it.
When cold and menthol are used together, the gate opens even more strongly. This helped the researchers capture the protein fully open, something they could not do with cold alone.
Why this matters for medicine
Problems with TRPM8 are linked to chronic pain, migraines, dry eye, and some cancers. One eye‑drop medicine, acoltremon, works by activating the same cooling pathway, helping tears flow and easing irritation.
The team also spotted a “cold spot” on the protein—a tiny region that is key for sensing temperature and keeping the gate responsive during long cold exposure.
Now that we understand how cold changes the protein’s shape, scientists have a clear map for designing new drugs that target this pathway.
Answering a long‑standing puzzle
These findings give the first molecular picture of how temperature and chemicals like menthol join forces to make us feel cool. The work solves a question that has puzzled sensory biologists for many years.