They’re on a hot streak. Researchers who last year discovered a mammalian cell-surface protein that senses coolness–and the presence of menthol–have now found a protein that enables nerve cells to recognize much colder temperatures (SN: 2/16/02, p. 101: Available to subscribers at Cool Discovery: Menthol triggers cold-sensing protein).
Whereas the cool-menthol receptor kicks in around 25C, the newly identified receptor doesn’t trigger nerve cells until the thermometer falls below 15C, Ardem Patapoutian of the Scripps Research Institute in La Jolla, Calif., and his colleagues report in the March 21 Cell. They had suspected that an additional temperature sensor exists because other scientists had recently documented nerve cells that respond to cold temperatures but not to menthol.
The two cold-activated receptors are related in structure, but their amino acid makeup is very different, the researchers report. Curiously, the new cold receptor is found on nerve cells that also sport a receptor for hot temperatures and capsaicin, the chemical that gives chilies and other foods their fiery kick.
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