One gap junction consists of a cluster of closely packed pairs of transmembrane channels, the connexons, through which materials of low MW diffuse from one cell to a neighboring cell. A connexon is composed of a hexamer of connexins. Interacts with CNST. Mice lacking both Gja12 and Gjb1 display a severe demyelination phenotype associated with oligodendrocyte death. These mice develop action tremors, tonic seizures, sporadic convulsions and loss of consciousness preceding death in the sixth week after birth. Belongs to the connexin family. Beta-type (group I) subfamily.