Transient receptor potential cation channel, subfamily A, member 1, also known as transient receptor potential ankyrin 1, TRPA1, or The Wasabi Receptor, is a protein that in humans is encoded by the TRPA1 (and in mice and rats by the Trpa1) gene. TRPA1 is an ion channel located on the plasma membrane of many human and animal cells. This ion channel is best known as a sensor for pain, cold and itch in humans and other mammals, as well as a sensor for environmental irritants giving rise to other protective responses (tears, airway resistance, and cough). Function TRPA1 is a member of the transient receptor potential channel family. TRPA1 contains 14 N-terminal ankyrin repeats and is believed to function as a mechanical and chemical stress sensor. One of the specific functions of this protein studies involves a role in the detection, integration and initiation of pain signals in the peripheral nervous system. It can be activated at sites of tissue injury or sites of inflammation directly by endogenous mediators or indirectly as a downstream target via signaling from a number of distinct G-protein coupled receptors (GPCRs), such as bradykinin. Recent studies indicate that TRPA1 is activated by a number of reactive (allyl isothiocyanate, cinnamaldehyde, farnesyl thiosalicylic acid, formalin, hydrogen peroxide, 4-hydroxynonenal, acrolein, and tear gases) and non-reactive compounds (nicotine, PF-4840154) and is thus considered as a "chemosensor" in the body. TRPA1 is co-expressed with TRPV1 on nociceptive primary afferent C-fibers in humans. This sub-population of peripheral C-fibers is considered important sensors of nociception in humans and their activation will under normal conditions give rise to pain. Indeed, TRPA1 is considered as an attractive pain target. TRPA1 knockout mice showed near complete attenuation of nocifensive behaviors to formalin, tear-gas and other reactive chemicals . TRPA1 antagonists are effective in blocking pain behaviors induced by inflammation (complete Freund's adjuvant and formalin). Although it is not firmly confirmed whether noxious cold sensation is mediated by TRPA1 in vivo, several recent studies clearly demonstrated cold activation of TRPA1 channels in vitro. In the heat-sensitive loreal pit organs of many snakes TRPA1 is responsible for the detection of infrared radiation. Snakes have this type of receptors in their pit organ to help them detect infrared radiation. However, frogs such as Hyalinobatrachium fleischmanni can reflect infrared light with their skins and if the environment also reflect infrared light, the frogs won't be discovered by the predators.