Laboratory of Ion Channel Research

A spontaneous phototransduction mutant in Drosophila displays transient receptor potentials (trp) in response to continuous light. Identification of the trp gene and recognition of its function as a Ca²⁺-permeable cation channel led to the cloning of many channels that bear sequence and structural similarities to the Drosophila TRP, which together form the TRP channel family and are subdivided into seven subfamilies.

• TRP channels are tetramers of four identical or similar subunits with six transmembrane domains (TM) and cytosolic N- and C-terminal tails. The fifth (TM5) and sixth (TM6) transmembrane segments and the connecting loop form the central cation-conducting pore. The domains TM1–TM4 and the cytoplasmic N- and C-terminal parts contain regulatory domains that control channel gating.
• TRPV5 and TRPV6 are Ca²⁺-selective (P_Ca/P_Na > 100), TRPM4 and TRPM5 are monovalent-selective (P_Ca/P_Na < 0.05), all other TRP channels are relatively nonselective.
• TRP channels are weakly voltage-sensitive, TRPV1, TRPM4, TRPM5, and TRPM8 being most sensitive to voltage changes.

Link: IUPHAR Receptor Database