Structural component of gap junctions (PubMed:15692151). Gap junctions are dodecameric channels that connect the cytoplasm of adjoining cells. They are formed by the docking of two hexameric hemichannels, one from each cell membrane (By similarity). Small molecules and ions diffuse from one cell to a neighboring cell via the central pore (PubMed:15692151). A hemichannel or connexon is composed of a hexamer of connexins. A functional gap junction is formed by the apposition of two hemichannels (By similarity). Forms heteromeric channels with GJB2 (PubMed:15692151). Colocalizes with GJB2 at gap junction plaques in the cochlea. Detected in cochlea (at protein level) (PubMed:15692151). Detected in cochlea (PubMed:15692151). Expressed in skin (PubMed:1512260). Detected in cochlea after 15 dpc. Detected in the spiral limbus in neoneates at 2, 8 and 10 days after birth, before the onset of hearing. Belongs to the connexin family. Beta-type (group I) subfamily.