gap junctions
Definition: A type of junction between two cells through which ions and small molecules can pass.
Gap junctions are small channels formed between neighbouring cells. They allow two-way intercellular communication between healthy cells by allowing the exchange of small molecules and ions (the second messengers) that affect cell communication and signalling. Six connexin proteins localized at the cell membrane are arranged in a similar manner to a camera diaphragm to form a connexon. Connexons from one cell dock with connexons from an adjacent cell to form a gap junction channel.
Gap-junction intercellular communication (GJIC)
Gap-junction intercellular communication (GJIC) allows a mechanism of synchronized cellular response to a variety of intercellualr signals by regulating the direct passage of low-molecular-weight metabolites (< 1000 daltons) and ions between the cytoplasm of adjacent cells.
Functional gap junction intercellular communication (GJIC) and cell signalling maintain homeostatic balance and enable healthy cells and tissue to respond to external stimuli. Conversely, disrupted GJIC is associated with almost all cancers, vascular and kidney diseases, and up to 70% of all neurodegenerative diseases.
See also
connexins
connexons
References
Sohl G, Maxeiner S, Willecke K. Expression and functions of neuronal gap junctions. Nat Rev Neurosci. 2005 Mar;6(3):191-200. PMID: #15738956#
van Steensel MA. Gap junction diseases of the skin. Am J Med Genet. 2004 Nov 15;131C(1):12-9. PMID: #15468169#
Falk M. Genetic tags for labelling live cells : gap junctions and beyond. Trends Cell Biol. 2002 Sep ;12(9):399-404. PMID : #12220850#