TRPA is a family of transient receptor potential ion channel

Ion channel

Ion channels are pore-forming proteins that help establish and control the small voltage gradient across the plasma membrane of cells by allowing the flow of ions down their electrochemical gradient. They are present in the membranes that surround all biological cells...

s.

The sole member of the TRPA sub-family, TRPA1, contains 14 N-terminal ankyrin

Ankyrin

Ankyrins are a family of adaptor proteins that mediate the attachment of integral membrane proteins to the spectrin-actin based membrane skeleton. Ankyrins have binding sites for the beta subunit of spectrin and at least 12 families of integral membrane proteins...

 repeats and is believed to function as a mechanical stress sensor. It is expressed in the dorsal root ganglion

Dorsal root ganglion

In anatomy and neuroscience, a dorsal root ganglion is a nodule on a dorsal root that contains cell bodies of neurons in afferent spinal nerves.-Unique unipolar structure:...

, trigeminal ganglion

Trigeminal ganglion

The trigeminal ganglion is a sensory ganglion of the trigeminal nerve that occupies a cavity in the dura mater, covering the trigeminal impression near the apex of the petrous part of the temporal bone.-Relations:It is somewhat crescentic in shape, with its convexity...

, and hair cells. The temperature sensitivity of TRPA1 is highly disputed, with some reports claiming that it is activated by noxiously cold stimuli and others disputing such a claim. TRPA1 is known to be activated by isothiocyanate

Isothiocyanate

Isothiocyanate is the chemical group –N=C=S, formed by substituting sulfur for oxygen in the isocyanate group. Many natural isothiocyanates from plants are produced by enzymatic conversion of metabolites called glucosinolates. These natural isothiocyanates, such as allyl isothiocyanate, are also...

s, which are the pungent chemicals in substances such as mustard oil

Mustard oil

The term mustard oil is used for three different oils that are made from mustard seeds:*A fatty vegetable oil resulting from pressing the seeds,...

 and wasabi

Wasabi

, also known as Japanese horseradish, is a member of the Brassicaceae family, which includes cabbages, horseradish, and mustard. Its root is used as a condiment and has an extremely strong flavor. Its hotness is more akin to that of a hot mustard rather than the capsaicin in a chili pepper,...

, methyl salicylate

Methyl salicylate

Methyl salicylate is a natural product of many species of plants. Some of the plants which produce it are called wintergreens, hence the common name.-Botanical background:...

 in winter green oil, and cinnamaldehyde

Cinnamaldehyde

Cinnamaldehyde is the organic compound that gives cinnamon its flavor and odor. This pale yellow viscous liquid occurs naturally in the bark of cinnamon trees and other species of the genus Cinnamomum...

in cinnamon, amongst numerous other substances.