Figure 1.

General characteristics of Cx and Cx-based channels. Panel (A) illustrates a representative topography of Cx at the plasma membrane. Connexin proteins are formed by four transmembrane domains, two extracellular loops (EL1 and EL2), one intracellular loop (IL), and both the N- and C-terminus are facing the cytoplasm. Panel (B) displays a hexamer of Cxs for a connexon or hemichannel. The channel presents a central pore through which, bidirectionally flow of ions and molecules up to ~1.2 kDa occurs. Panel (C) shows the formation of a gap junction channel (GJC) by serial docking of two hemichannels at the cell-to-cell contact. GJC allow the exchange of ion and molecules between the cytoplasm of neighboring cells.