Figure 2. Structure of gap junctions. Gap junctions located at the cell plasma membrane are built up by 2 hemichannels that each contain 6 connexin proteins. Connexin proteins consist of 4 transmembrane domains (TM1-4), one cytoplasmic loop (CL), 2 extracellular loops (EL), one cytoplasmic C-terminal tail (CT) and one cytoplasmic N-terminal tail.
