Five canonical tastes, i.e. bitter, sweet, umami (amino acids), salty and sour (acids) are detected by animals as diverse as fruit flies and humans, consistent with a near-universal drive to consume fundamental nutrients and to avoid toxins or other harmful compounds. In the last few years a high number of scientific sign of progress have been made in the studying and discovery of the molecular mechanisms behind the sweet, bitter and umami tastes whereas sour taste mechanisms are still poorly understood and investigated. Only recently, few studies pointed out that the sour transduction mechanism may be mediated by the Otopetrins, a family of trans-membrane proteins which are deemed to play an important role in the H+ permeation through the ion channel.