Membrane channel - Misplaced Pages

Membrane channels are 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. Insights have suggested endocannabinoids (eCBs) as molecules that can regulate the opening of these channels during diverse conditions.

Properties

Hemichannels

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

Pannexin

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. 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.

References

Labra VC, Santibáñez CA, Gajardo-Gómez R, Díaz EF, Gómez GI, Orellana JA (2018-03-20). "The Neuroglial Dialog Between Cannabinoids and Hemichannels". Frontiers in Molecular Neuroscience. 11: 79. doi:10.3389/fnmol.2018.00079. PMC 5890195. PMID 29662436.
^ Retamal MA (2014). "Connexin and Pannexin hemichannels are regulated by redox potential". Frontiers in Physiology. 5: 80. doi:10.3389/fphys.2014.00080. PMC 3933782. PMID 24611056.
Spray DC, Ye ZC, Ransom BR (November 2006). "Functional connexin "hemichannels": a critical appraisal". Glia. 54 (7): 758–73. CiteSeerX 10.1.1.124.4117. doi:10.1002/glia.20429. PMID 17006904. S2CID 17677517.
^ Baroja-Mazo A, Barberà-Cremades M, Pelegrín P (January 2013). "The participation of plasma membrane hemichannels to purinergic signaling". Biochimica et Biophysica Acta (BBA) - Biomembranes. 1828 (1): 79–93. doi:10.1016/j.bbamem.2012.01.002. PMID 22266266.

Calcium-activated	BK channel α1 β1 β2 β3 β4 SK channel SK1 SK2 SK3 IK channel IK1 K_Ca 1.1 2.1 2.2 2.3 3.1 4.1 4.2 5.1
Inward-rectifier	K_ATP K_ir 1.1 2.1 2.2 2.3 2.4 2.6 GIRK/K_ir 3.1 3.2 3.3 3.4 K_ir 4.1 4.2 5.1 6.1 6.2 7.1
Tandem pore domain	K2P 1 2 3 4 5 6 7 9 10 12 13 15 16 17 18
Voltage-gated	K_vα1-6 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 2.1 2.2 3.1 3.2 3.3 3.4 4.1 4.2 4.3 5.1 6.1 6.2 6.3 6.4 K_vα7-12 7.1 7.2 7.3 7.4 7.5 8.1 8.2 9.1 9.2 9.3 10.1 10.2 11.1/hERG 11.2 11.3 12.1 12.2 12.3 K_vβ 1 2 3 KCNIP 1 2 3 4 minK/ISK minK/ISK-like MiRP 1 2 3 Shaker (gene)

Miscellaneous

Cl: Chloride channel	Calcium-activated chloride channels Anoctamin ANO1 Bestrophin 1 2 Chloride Channel Accessory 1 2 3 4 CFTR CLCN 1 2 3 4 5 6 7 KA KB CLIC 1 2 3 4 5 6 L1 CLNS 1A 1B
H: Proton channel	HVCN1
M: CNG cation channel	α 1 2 3 4 β 1 2 3 HCN FC 1 2 3 4
M: TRP cation channel	TRPA (1) TRPC 1 2 3 4 4AP 5 6 7 TRPM 1 2 3 4 5 6 7 8 TRPML 1 2 3 TRPN TRPP 1 2 TRPV 1 2 3 4 5 6
H₂O (+ solutes): Porin	Aquaporin 0 1 2 3 4 5 6 7 8 9 Voltage-dependent anion channel 1 2 3 General bacterial porin family
Cytoplasm: Gap junction	Connexin A GJA1 GJA3 GJA4 GJA5 GJA8 GJA9 GJA10 B GJB1 GJB2 GJB3 GJB4 GJB5 GJB6 GJB7 C GJC1 GJC2 GJC3 D GJD2 GJD3 GJD4 Innexin

By gating mechanism

Ion channel class	Ligand-gated Light-gated Voltage-gated Stretch-activated

see also disorders

Category:

Membrane biology

Properties

Hemichannels

Pannexin

References

Further reading