The transient receptor potential ion channel TRPA1 is a Ca2+-permeable nonselective cation channel widely expressed in sensory neurons, but also in many nonneuronal tissues typically possessing barrier functions, such as the skin, joint synoviocytes, cornea, and the respiratory and intestinal tracts. Here, the primary role of TRPA1 is to detect potential danger stimuli that may threaten the tissue homeostasis and the health of the organism. The ability to directly recognize signals of different modalities, including chemical irritants, extreme temperatures, or osmotic changes resides in the characteristic properties of the ion channel protein complex. Recent advances in cryo-electron microscopy have provided an important framework for understanding the molecular basis of TRPA1 function and have suggested novel directions in the search for its pharmacological regulation. This chapter summarizes the current knowledge of human TRPA1 from a structural and functional perspective and discusses the complex allosteric mechanisms of activation and modulation that play important roles under physiological or pathophysiological conditions. In this context, major challenges for future research on TRPA1 are outlined.

• Keywords
• Chemosensation, Gating, Nociception, Sensory transduction, TRPA1 channel, Thermosensation,
• MeSH
• Allosteric Regulation MeSH
• Cryoelectron Microscopy methods   MeSH
• Transient Receptor Potential Channels metabolism   chemistry   physiology   MeSH
• TRPA1 Cation Channel * metabolism   chemistry   physiology   MeSH
• Humans MeSH
• Structure-Activity Relationship MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Transient Receptor Potential Channels MeSH
• TRPA1 Cation Channel * MeSH
• TRPA1 protein, human MeSH Browser

Transient receptor potential ankyrin 1 channel (TRPA1) serves as a key sensor for reactive electrophilic compounds across all species. Its sensitivity to temperature, however, differs among species, a variability that has been attributed to an evolutionary divergence. Mouse TRPA1 was implicated in noxious cold detection but was later also identified as one of the prime noxious heat sensors. Moreover, human TRPA1, originally considered to be temperature-insensitive, turned out to act as an intrinsic bidirectional thermosensor that is capable of sensing both cold and heat. Using electrophysiology and modeling, we compare the properties of human and mouse TRPA1, and we demonstrate that both orthologues are activated by heat, and their kinetically distinct components of voltage-dependent gating are differentially modulated by heat and cold. Furthermore, we show that both orthologues can be strongly activated by cold after the concurrent application of voltage and heat. We propose an allosteric mechanism that could account for the variability in TRPA1 temperature responsiveness.

• Keywords
• TRP channel, ankyrin receptor subtype 1, noxious cold, noxious heat, thermoTRP, transient receptor potential,
• MeSH
• Models, Biological MeSH
• Species Specificity MeSH
• Electrophysiology methods   MeSH
• HEK293 Cells MeSH
• TRPA1 Cation Channel metabolism   MeSH
• Humans MeSH
• Mice MeSH
• Voltage-Dependent Anion Channels metabolism   physiology   MeSH
• Cold Temperature MeSH
• Amino Acid Sequence MeSH
• Hot Temperature MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• TRPA1 Cation Channel MeSH
• Voltage-Dependent Anion Channels MeSH
• TRPA1 protein, human MeSH Browser
• Trpa1 protein, mouse MeSH Browser