Gap Junction Protein

Gap junction proteins are integral membrane proteins that assemble to form gap junctions—specialized intercellular connections that facilitate direct communication between adjacent cells. These channels allow the passage of ions, metabolites, and small signaling molecules (up to approximately 1 kDa) directly from the cytoplasm of one cell to another. In vertebrates, gap junctions are primarily formed by connexin proteins. In invertebrates, innexin proteins serve a similar function. Pannexins are structurally related but mainly function as single-membrane channels. A typical gap junction channel consists of two hemichannels (connexons), each contributed by neighboring cells. Connexins have four transmembrane domains, two extracellular loops, one intracellular loop, and cytoplasmic N- and C-terminal regions. Gap junctions enable rapid exchange of ions, metabolites, nucleotides, amino acids, and secondary messengers, direct electrical coupling between excitable cells, and coordination of cellular activities during development, differentiation, neural activity, and immune responses. Mutations in specific connexins cause various inherited diseases.

Other names

ConnexinInnexinPannexinGap junction channel