The Transient Receptor Potential (TRP) family of ion channels consists of a large number of proteins that are mostly permeable to both monovalent and divalent cations. The 30 mammalian TRP channels can be subdivided into six main subfamilies: TRPC (canonical, C1, C3 - 7), TRPV (vanilloid, V1 - 6), TRPM (melastatin, M1 - 8), TRPML (mucolipin, L1 - 3), TRPP (polycystin, P2, 3, 5) and TRPA (ankyrin, A1).
TRP channels are expressed in almost every tissue and cell type and play an important role in the regulation of various cell functions: vision, olfaction, taste, mechanosensation, osmoregulation and thermosensation. TRP channels, share a similar architecture of six-transmembrane domains with both cytoplasmic amino and carboxy termini.
Transient Receptor Potential Vanilloid 1 (TRPV1), the archetypal TRP channel, is mostly expressed on pain sensing nerves, is involved in the transmission and modulation of pain, and represents an important integrative station of responses to inflammatory mediators. The activation of TRPV1 caused by endogenous lipids (endovanilloids), by acidic media (low pH) and by high temperatures leads to a strong sensation of burning soreness or real pain.
Other TRP channels such as TRPV2, TRPV3, TRPV4, TRPM8 and TRPA1 are expressed on peripheral sensory neurons as well (see figure).