Gap junction channel (GJC)

Gap junction channels are specialized intercellular conduits that permit direct, regulated exchange of ions, small metabolites, and signaling molecules between adjacent cells. In vertebrates, these channels are hexameric assemblies of connexin proteins (connexons) from one cell docking with connexons from the neighboring cell to form a functional channel spanning the intercellular gap. The channel diameter allows passage of molecules up to ~1 kDa, contributing to rapid electrical and metabolic communication in tissues such as heart, brain, and epithelial layers. The functional properties of a gap junction channel are determined by its connexin composition, which can be homo- or heteromeric, granting tissue- and context-specific permeability and gating behavior. Mutations or dysregulation of connexin expression underlie diseases such as arrhythmias, deafness, neurodegeneration, and cancer. Gap junction channels are attractive drug targets but pose safety and specificity challenges due to essential roles in normal physiology.

Other names

Connexin channelIntercellular channelNexus (historically)Gap junction protein channel (less common)

Channel blockade (drugs prevent passage of ions/metabolites by occluding the pore or destabilizing channel formation) Allosteric modulation (changes gating or permeability) Phosphorylation state alteration (affects channel open/close state via kinases/phosphatases) Modulation of channel protein expression or assembly