Gap channels (also known as gap junctions) are specalized cell-cell contacts between almost all eukaryotic cells that provide direct intracellular communication. Generally, gap channels allow the passive diffusion of molecules up to 1 kDa which includes nutrients, small metabolites (e.g. glucose), ions (K+, Ca2+) and second messengers (IP3, cAMP and cGMP).
Gap channels allow electrical and biochemical coupling between cells and in excitable tissues, such as neurons and the heart, enables the generation of synchronized and rapid responses. Structurally, gap channels are composed of two hemichannels called 'connexons', which themselves are formed from six connexin molecules. Homo- and heteromeric combinations are seen, which exhibit distinct permeability, selectivity and functional properties.
Pannexins are related to connexins and can also form gap junctions. However, their expression is limited to the brain. Furthermore, in nonchordate animals a family of proteins called innexins form these channels.
Gap channels are regulated through post-translational modifications of the C'-terminal cytoplasmic tail and phosphorylation modulates assembly and their physiological properties. They are continuously synthesized and degraded, allowing tissues to rapidly adapt to changing environmental conditions.
Connexins play a key role in many physiological processes including cardiac and smooth muscle contraction, regulation of neuronal excitability, epithelial electrolyte transport and keratinocyte differentiation. Mutations in connexin genes are associated with human diseases including sensorineural deafness, a variety of skin disorders, peripheral neuropathy and cardiovascular disease.
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|Gene||Species||Gene Symbol||Gene Accession No.||Protein Accession No.|
Gap Junction Protein α1
Gap Junction Protein α3
|View all Connexin and Pannexin Gene Data »|
Literature for Gap Channels
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