Liman Lab Reveals Mechanism of Sour Taste
Lab at USC definitively establishes the proton ion channel OTOP1 as a sour taste sensor.
The protein responsible for detecting sour in taste buds has been difficult to identify. This is partly because sour chemicals are detected both through the sense of taste (taste perception) and through the production of pain (somatosensory perception). Thus, simple taste preference tests with mice are inconclusive. Even without the taste pathway, mice still avoid sour-tasting liquids. Advances in the technologies that enable researchers to determine gene expression and perform genetic engineering mice have led to the discovery of the sour taste sensor.
The Liman lab has been studying sour taste for many years. In 2018, her lab identified a candidate sensor for sour tasting-chemicals, the protein otopetrin 1 (OTOP1). This year, her lab provided key evidence that OTOP1 is a critical sensor for the tongue to signal the brain about sour tastes.
Sour is one of 5 tastes: Sour, sweet, salty, umami, and bitter. The receptors that bind chemicals for the other five tastes are all known, but the receptor or sensor for sour-tasting chemicals has been elusive.
Taste occurs when chemicals wash across specialized cells in the mouth and on the tongue. Taste buds…
