Ion channels are proteins forming a pore that allows the flow of ions across membranes. Ion channels are voltage- or second messager-gated. Some of these proteins, especially sodium and potassium channels, are involved in the transmission of pain signals to the central nervous system and are promising targets for the development of pain therapeutics. Ion channels, such as TRPV1, TRPM8, TRPA1, hERG, TREK1, P2X, ASIC or voltage-gated sodium channels have been identified as interesting channels, although there is no experimental data (X-ray, NMR) available on the atomic structure of the different ion channels. Click on the different receptors to get more information, homology models or docking results.
The Figure lists the most common ion channels. Red arrows show channels, that are relevant for pain.
Ion channels are made by living cells. A lot of them have similar filters, shown at the top in the two examples. These are connected to specialized gating domains, shown at the bottom. The membrane is shown schematically with a gray stripe and only two of the four chains are shown in the selectivity filters, so the pore is visible. The gating domains open and shut the channel based on different signals, such as voltage or the presence of key signaling molecules. Several structural mechanisms are used for opening and closing potassium channels. In the two simple bacterial channels shown here, protein domains connected to the channel are thought to twist the four chains of the channel.