Connexins

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Connexins
Connexins
Scheme drawing
Identifier
Gene name (s) CX, CXN
Transporter classification
TCDB 1.A.24
designation Connexin family
Occurrence
Parent taxon Chordates

structure

As connexins refers to a family of transmembrane proteins , in cells the gap junctions form and the direct exchange of molecules up to a size of about 1  kDa allow between adjacent cells.

To date, 21 different connexins are known in humans and 20 connexins in mice. Their size varies between 23 kDa and 62 kDa. They have four transmembrane domains with two extracellular loops made up of anti-parallel β-sheets.

Six connexins are stored in the membrane to form a connexon that surrounds a pore. Two connexons of two adjacent membranes form a gap junction channel.

There are two different systems for the nomenclature of the connexins. According to a nomenclature , the name is made up of the abbreviation Cx and the theoretical molar mass (e.g. Cx43; possibly combined with a species abbreviation). In another nomenclature, the connexins are divided into different groups based on their sequence homology.

In addition to the brain form neurons highly specialized glial cells with each gap junctions made. Connexin 43 is found primarily in astrocytes , while oligodendrocytes express connexin 32.

A mutation in the connexin 26 gene is responsible for 11–37% of all sporadic cases of recessively inherited hearing loss . Connexin 26 is primarily localized in cell structures in the inner ear . Since it can also combine with connexin 30, this is included in the genetic diagnosis for investigations for mutations by means of DNA sequencing.

Web links

Commons : connexins  - collection of images, videos and audio files

Individual evidence

  1. ↑ Beyer, EC, Goodenough, DA, and Paul, DL (1988) Int. Rev. Cytol. 137c, 231-242.