Connexon

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Connexon is the assembly of 6 subunits of protein connexin with a hollow center that forms a channel through the plasma membrane at a gap junction[1]. A single gap junction may consist of a few or as many as thousands of clustered connexons. Each connexon has a diameter of about 7 nm and a hollow center that forms a very thin hydrophilic channel through the membrane. The channel is about 3 nm in diameter which only allow small molecules and ions to pass through, while not large enough to provide passage for large molecules such as proteins. When the connexon from adjacent cells meet, the hollow cylinders in the two membranes join from end to end, forming direct channels of communication between two cells. When the channel open, the connected cells function like a single cell that contains multiple nuclei (a syncytium)[2].

The connexon allows for electrical charges to be passed between the adjacent cells without the need of a chemical synapse. This removes the delay that a synapse would create, which is why they are useful in the heart for creating betting synchronisation between contractions[3].

References

  1. Jeff Hardin, Gregory Bertoni and Lewis J. Kleinsmith, 2012. Becker’s World of the Cell, Eighth Edition. Chapter 17. PG 486.
  2. Dee Unglaub Silverthorn, 2016. Human Physiology: An integrated approach, Seventh Edition. Chapter 6. PG 190.
  3. Alberts et. al. Molecular Biology of The Cell, 6th edition, New York: Garland Science 2015.
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