Schematic representation of connexin-based gap junction plaques.
Six individual connexin molecules form a single hemichannel. Hemichannels align and dock with a corresponding hemichannel in the neighbouring cell to form a holochannel. Molecules can pass from one cell to the other via the holochannel pore. Hemichannels also function in the release of certain molecules from within a cell into the extracellular milieu. This description is based on the widely-accepted model for connexin-based channel structure. It is anticipated that innexin- and pannexin- based channels will be broadly similar, structurally, to connexin channels.