Figure 1. Heptameric structure of the pannexin 1 channel.

Side view (left) of the pannexin 1 structure resolved by Michalski et al., and top views of the extracellular region (EC; top right), the transmembrane region (TM; middle right), and the intracellular region (IC; bottom right). The arrangement of seven subunits to form the channel is clearly visible in the structure. Each of the three regions shown in the top views contains a constriction site in the pore that runs through the center of the protein, and the amino acid residues involved in the constriction sites are represented as pink spheres. Protein data bank ID: 6VD7. CT: C-terminus (yellow); NT: N-terminus (red).