Charles Zuker and his colleagues have identified a protein that detects sour taste on the tongue and may help to warn mammals of acidic, spoiled and unripe food.
The researchers show that the protein, an ion channel called PKD2L1, is found in certain taste receptor cells and that mice genetically engineered to lack these cells cannot respond to sour-tasting stimuli, such as citric acid. The study, reported in Nature (Vol. 442, No. 7105, 24 August 2006), adds to the previous identification by the same group of cell types that mediate sweet, bitter and umami tastes.
The PKD2L1 receptor is also active in certain neurons in the spinal cord and may, the authors propose, be involved in detecting the acidity of cerebrospinal fluid, suggesting a common mechanism for detection of acidity in different parts of the body.
Charles Zuker (University of California, La Jolla, CA, USA)
(C) Nature press release.
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