Cx26 | Connexin 26
Connexins form so-called gap junctions. Each gap junction is composed of two hemichannels, or connexons, which consist of homo- or heterohexameric arrays of connexins, and the connexon in one plasma membrane docks end-to-end with a connexon in the membrane of a closely opposed cell. The hemichannel is made of six connexin subunits which are themselves each constructed out of six connexin molecules. Connexins contain four highly ordered transmembrane segments (TMSs). The connexin gene family is diverse, with twenty-one identified members in the sequenced human genome.
Connexins (Cx) are structurally related transmembrane proteins that assemble to form vertebrate gap junctions. Gap junctions are essential for many physiological processes, such as the coordinated depolarization of cardiac muscle, proper embryonic development, and the conducted response in microvasculature. By forming a syncytium between cell, connexins provide electric coupling and direct cell-cell communication of small molecules.
Cx26 Background Information
Gap junction beta-2 protein (GJB2), also known as connexin 26 (Cx26) is a structural component of gap junctions. Mutations in this gene are responsible for hearing loss. Connexin-associated deafness is thought to be the result of defective development of auditory sensory epithelium due to connexion dysfunction. Furthermore, mutations in this gene are associated with skin disorders.
Expressed in the cochlea, weakly in the suprabasal layer of the epidermis and in epithelial cells of the mammary gland and endometre
Acts via forming gap junctions by enhancing intercellular electrical and chemical transmission (passive diffusion of low molecular weight materials up to 1 kDa, including nutrients, metabolites (glucose), ions and second messengers (IP3, cAMP)). Cx26 assembles to form channels between cells in the cochlear supporting cells, allowing the rapid removal of K+ away from the base of hair cells, resulting in the recycling of this ion back to the endolymph to maintain cochlear homeostasis
Deafness, autosomal recessive, 1A (DFNB1A), Deafness, autosomal dominant, 3A (DFNA3A), Vohwinkel syndrome (VOWNKL), Keratoderma, palmoplantar, with deafness (PPKDFN), Keratitis-ichthyosis-deafness syndrome (KID syndrome), Knuckle pads, leukonychia, and sensorineural deafness (KPLD) may be caused by mutations of GJB2.
Interacts with further connexins (GJA3, GJA8, GJB1, GJB2, GJB3, GJB6), CNST, SKP1
Flufenamic acid, carbenoxolone, octanol, extracellular Ca2+
& Bilayer recordings on Port-a-Patch and Orbit mini
Reviews and Links
- Roberto Bruzzone (2001) Learning the language of cell-cell communication through connexin channels. Genome Biology 2(11):reports4027.1–4027.5
- Ryo Yamasaki (2018) Connexins in health and disease. Clinical and Experimental Neuroimmunology 9(1): 30–36
Transporter classification database: