Gap junctions

In cell phys, we briefly talked about the biological importance of gap junctions, which are relatively small pores that connect adjacent cells. These junctions are important for biochemistry because it allows some small molecules and ions to passively diffuse from cell to cell. The gap junction complex is formed from two different connexon complexes, and both of the adjacent cells contain one of these complex which are lined up across from each other, spanning the extracellular space. The connexons are transmembrane proteins which are made up of six different identical subunits (which are themselves four-pass transmembrane proteins) that can rotate to open or close the pore. One of the most important biological uses for this is in neuronal cells, where membrane potential can quickly be passed from cell to cell as ions diffuse through the gap junctions.