Membrane channel

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A family of biological membrane proteins which allow the passive movement of ions (ion channels), water (aquaporins) or other solutes to passively pass through the membrane down their electrochemical gradient. They are studied using a range of channelomics experimental and mathematical techniques.



A hemichannel is a membrane channel made up of six subunits.[1] A hemichannel is defined as one-half of a gap junction channel.[2] Hemichannels consist of connexins.[1]


Pannexins are involved in the process of purinergic signalling. They release Adenosine triphosphate (ATP), which activate purinergic receptors. On the other hand, purinergic receptor activation can also lead to the opening of the channel, via a positive feedback loop.[3] In addition, P2Y receptors activate inositol trisphosphate, which leads to a transient increase in intracellular calcium, and opens both connexin and pannexin channels, therefore contributing to the propagation of calcium waves across astrocytes and epithelial cells.[3]


  1. ^ a b Retamal, Mauricio A. (2014). "Connexin and Pannexin hemichannels are regulated by redox potential". Frontiers in Physiology. 5. PMC 3933782Freely accessible. PMID 24611056. doi:10.3389/fphys.2014.00080. 
  2. ^ Spray, David C.; Ye, Zu-Cheng; Ransom, Bruce R. (15 November 2006). "Functional connexin "hemichannels": A critical appraisal". Glia. 54 (7): 758–773. doi:10.1002/glia.20429. 
  3. ^ a b Baroja-Mazo, Alberto; Barberà-Cremades, Maria; Pelegrín, Pablo (January 2013). "The participation of plasma membrane hemichannels to purinergic signaling". Biochimica et Biophysica Acta (BBA) - Biomembranes. 1828 (1): 79–93. PMID 22266266. doi:10.1016/j.bbamem.2012.01.002. 

Molecular Biology of the Cell 4th ed. Alberts, B.; Johnson, A.; Lewis, J.; Raff, M.; Roberts, K.; Walter, P. New York and London: Garland Science; c2002 See Glossary, under "membrane channels". This book is available online