Cx43 | Connexin 43
Connexins form so-called gap junctions. Each gap junction is composed of two hemichannels, or connexons, which consist of homo- or heterohexameric arrays of connexins, and the connexon in one plasma membrane docks end-to-end with a connexon in the membrane of a closely opposed cell. The hemichannel is made of six connexin subunits which are themselves each constructed out of six connexin molecules. Connexins contain four highly ordered transmembrane segments (TMSs). The connexin gene family is diverse, with twenty-one identified members in the sequenced human genome.
Connexins (Cx) are structurally related transmembrane proteins that assemble to form vertebrate gap junctions. Gap junctions are essential for many physiological processes, such as the coordinated depolarization of cardiac muscle, proper embryonic development, and the conducted response in microvasculature. By forming a syncytium between cell, connexins provide electric coupling and direct cell-cell communication of small molecules.