How do gap junctions occur?

Aqueous channels, made up of six connexins in each cell of the two communicating cells, named connexon, extend from one cytosol to another, tightly linked by interactions with extracellular domains in intercellular space, space between two adjacent plasma membranes in 3 nm (diameter of DNA), each connexin is integral polytopic protein having four alpha-helix domains, which is hyrophobic (excepy long one), since all hydrophilic sides are directed towards channel centre, a hydrophillic channel (1.5-2 nm diameter) is formed allowing the flow of polar molecules (not selectively) However it is controlled into one direction (reverse rotation for both sides of the connexon.