Researchers at UCSF, led by David Julius, built a library of genes from rat sensory neurons and tested them in human kidney cells grown in the lab, searching for the one gene that responds to capsaicin, the compound that makes chili peppers burn.
In 1997, the search isolated one gene, later named TRPV1, that made the human cells respond to capsaicin with a rush of calcium. The same channel also opened in response to painful heat, meaning a single molecule could detect both the burn of a chili pepper and dangerous warmth.
David Julius shared the 2021 Nobel Prize in Physiology or Medicine with Ardem Patapoutian, who separately identified the PIEZO channels behind the sense of touch and body position, and the Nobel committee grouped the two discoveries as explaining how the nervous system senses temperature and pressure at the molecular level. Drugs targeting TRPV1 for chronic pain have been explored since, with mixed results so far in human trials.
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One chili-pepper protein explained how the body feels heat.
Source
- Caterina, M. J., Schumacher, M. A., Tominaga, M., Rosen, T. A., Levine, J. D., & Julius, D. (1997). The capsaicin receptor: a heat-activated ion channel in the pain pathway. Nature, 389(6653), 816–24. https://doi.org/10.1038/39807