Gap Junction Protein

Gap junction (GJ) channels span the plasma membranes of adjacent cells and are formed by the docking of two hemichannels (connexons) oligomerized from connexin (Cx) proteins, which consist of 21 distinct isoforms. GJs provide a direct pathway for cell-to-cell electrical signaling and metabolic communication, allowing the passage of small ions, amino acids, metabolites, tetraethylammonium and signaling molecules such as cAMP, IP3, siRNA and small peptide.

Gap junction channels provide the basis for intercellular communication in the cardiovascular system for maintenance of the normal cardiac rhythm, regulation of vascular tone and endothelial function as well as metabolic interchange between the cells. In the heart, GJs mediate electrical coupling between cardiac myocytes, forming the cell-to-cell pathways for orderly spread of the wave of electrical excitation responsible for synchronous contraction. Gap junctions also play an important role in the control of bladder contractile response and in the regulation of various immune inflammatory processes.