PerspectiveBiophysics

pHirst sour taste channels pHound?

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Science  02 Mar 2018:
Vol. 359, Issue 6379, pp. 991-992
DOI: 10.1126/science.aas9772

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Summary

Do you enjoy the tartness of apples or grapes? A touch of sour can be delicious. But, highly sour foods are repulsive. This reaction warns against consuming foods spoiled by bacterial growth, such as rancid milk. So, it is no surprise that many animals have a sense of sour taste. In humans, it is one of five basic tastes, which also include sweet, bitter, salty, and umami (the savory taste induced by l-glutamate). Many receptors and ion channels in taste buds that are critical for detecting these chemicals in foods are now known (1). However, a mammalian sour taste receptor has been elusive. On page 1047 of this issue, Tu et al. (2) reveal a previously unrecognized H+-selective channel that functions in mouse taste receptor cells (TRCs, which occur in taste buds of the tongue) that are essential for sour taste. This protein, Otopetrin1 (OTOP1), was originally identified because of its requirement in the vestibular system to maintain balance and to perceive gravity and limb orientation (3). The work by Tu et al. not only provides a strong candidate for the mammalian sour taste receptor but also raises questions concerning the broader roles of OTOP channels.