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. Plays an essential role in gap junction communication in the ventricles (By similarity). Plays a role in regulation of fin bone size and growth. A connexon is composed of a hexamer of connexins. Interacts with TMEM65. Localizes at the intercalated disk (ICD) in cardiomyocytes and proper localization at ICD is dependent on TMEM65. Expressed in adult ovary, heart, lens and liver. In growing caudal fins, expressed in cells flanking the germinal region of newly growing segments and in osteoblasts at segment boundaries. Expressed both maternally and zygotically. Zygotic expression is initiated before gastrulation and persists through to day 5 of development. Levels increase in late somitogenesis, and late embryonic and early larval stages. Embryonic expression is observed in many developing tissues and organs, including the notochord and brain, and heart and vasculature. Detected throughout the lens at 24 hours post-fertilization (hpf), but by 3-4 days development, restricted to the lateral epithelium and differentiating cells in the equatorial region. Morpholino knockdown of the protein results in heart folding defects, reduced hematopoiesis and small eyes. Belongs to the connexin family. Alpha-type (group II) subfamily.