Gap channels (gap junctions)

Gap channels (gap junctions) are collections of intracellular channels that connect the cytoplasm of adjoining cells and permit direct cell-cell transfer of ions and small molecules. Gap junctions mediate intercellular communication. Connexins are transmembrane proteins and constitute a gap junction channel when six connexin subunits assemble into a hemichannel (connexon) which docks to another hemichannel located in a neighboring cell.