Connexin 32, Connexin 50, <cytosol> Na('+) = <extracellular region> Na('+), Occludin, ZO-1, <extracellular region> K('+) = <cytosol> K('+), <cytosol> K('+) = <extracellular region> K('+), Connexin 45, Connexin 40, Tubulin heterodimers (in microtubules), Connexin 46, Tubulin alpha, Tubulin beta, Connexin 43, Connexin 37, Connexin 26, Connexin 46, Actin, ZO-3, Cingulin, ZO-2, K(+) cytosol, Connexin 50, c-Src, Connexin 37, Connexin 43, Connexin 45, K(+) , Na(+), Connexin 40, PKC, <extracellular region> Na('+) = <cytosol> Na('+), Connexin 32, Caveolin-1, Connexin 31, Connexin 36, Na(+) cytosol
Gap junction channels are intercellular channels that allow passage of ions, such as K(+) and Na(+), and other small molecules between neighboring cells. These channels are formed from two multimeric subunits called hemichannels, or connexons, that reside in plasma membranes of two closely opposed cells.
Connexons are composed of six transmembrane protein subunits called Connexins . The double membrane channel, or gap junction, is generated directly and couples the cytoplasms of the interacting cells. This leads to integration and co-ordination of the cellular metabolism, signaling and function, e.g.,secretion or contraction in cell assemblies .
Interactions of Connexins with Zona occludens proteins ( ZO-1, ZO-2 and ZO-3 ) couple gap junction channels with the tight junction components, such as Occludin, and with cytoskeletal elements, such as Actin filaments .