Calcium channel
A calcium channel is an ion channel which shows selective permeability to calcium ions. It is sometimes synonymous with voltage-gated calcium channel,[1] although there are also ligand-gated calcium channels.[2]
Comparison tables
The following tables explain gating, gene, location and function of different types of calcium channels, both voltage and ligand-gated.
Voltage-gated
| Type | Voltage | α1 subunit (gene name) | Associated subunits | Most often found in |
| L-type calcium channel ("Long-Lasting" AKA "DHP Receptor") | HVA (high voltage activated) | Cav1.1 (CACNA1S) Cav1.2 (CACNA1C) Cav1.3 (CACNA1D) Cav1.4 (CACNA1F) | α2δ, β, γ | Skeletal muscle, smooth muscle, bone (osteoblasts), ventricular myocytes** (responsible for prolonged action potential in cardiac cell; also termed DHP receptors), dendrites and dendritic spines of cortical neurons |
| N-type calcium channel ("Neural"/"Non-L") | HVA (high-voltage-activated) | Cav2.2 (CACNA1B) | α2δ/β1, β3, β4, possibly γ | Throughout the brain and peripheral nervous system. |
| P-type calcium channel ("Purkinje") /Q-type calcium channel | HVA (high voltage activated) | Cav2.1 (CACNA1A) | α2δ, β, possibly γ | Purkinje neurons in the cerebellum / Cerebellar granule cells |
| R-type calcium channel ("Residual") | intermediate-voltage-activated | Cav2.3 (CACNA1E) | α2δ, β, possibly γ | Cerebellar granule cells, other neurons |
| T-type calcium channel ("Transient") | low-voltage-activated | Cav3.1 (CACNA1G) Cav3.2 (CACNA1H) Cav3.3 (CACNA1I) | neurons, cells that have pacemaker activity, bone (osteocytes), thalamus (thalamus) |
Ligand-gated
- the receptor-operated calcium channels (in vasoconstriction)
| Type | Gated by | Gene | Location | Function |
| IP3 receptor | IP3 | ITPR1, ITPR2, ITPR3 | ER/SR | Releases calcium from ER/SR in response to IP3 by e.g. GPCRs[4] |
| Ryanodine receptor | dihydropyridine receptors in T-tubules and increased intracellular calcium (Calcium Induced Calcium Release - CICR) | RYR1, RYR2, RYR3 | ER/SR | Calcium-induced calcium release in myocytes[4] |
| Two-pore channel | Nicotinic acid adenine dinucleotide phosphate (NAADP) | TPCN1, TPCN2 | endosomal/lysosomal membranes | NAADP-activated calcium transport across endosomal/lysosomal membranes[5] |
| Cation channels of sperm | Calcium (CICR) | PKD2 family | sperm (specifically flagella) | Non-selective calcium-activated cation channel directing sperm in female reproductive tract[6] |
| store-operated channels | indirectly by ER/SR depletion of calcium[4] | ORAI1, ORAI2, ORAI3 | plasma membrane | Provides calcium signaling to the cytoplasm[7] |
Pharmacology
L-type calcium channel blockers are used to treat hypertension. In most areas of the body, depolarization is mediated by sodium influx into a cell; changing the calcium permeability has little effect on action potentials. However, in many smooth muscle tissues, depolarization is mediated primarily by calcium influx into the cell. L-type calcium channel blockers selectively inhibit these action potentials in smooth muscle which leads to dilation of blood vessels; this in turn corrects hypertension.[8]
T-type calcium channel blockers are used to treat epilepsy. Increased calcium conductance in the neurons leads to increased depolarization and excitability. This leads to a greater predisposition to epileptic episodes. Calcium channel blockers reduce the neuronal calcium conductance and reduce the likelihood of experiencing epileptic attacks.[9]
See also
- Calcium in biology – Use of calcium by organisms.
References
- ^ "" at Dorland's Medical Dictionary
- ^ Striggow F, Ehrlich BE (August 1996). "Ligand-gated calcium channels inside and out". Current Opinion in Cell Biology. 8 (4): 490–495. doi:10.1016/S0955-0674(96)80025-1. PMID 8791458.
- ^ Boron WF (2005). Medical Physiology: A Cellular And Molecular Approach. Elsevier/Saunders. ISBN 1-4160-2328-3. Page 479
- ^ a b c Rang HP (2003). Pharmacology. Edinburgh: Churchill Livingstone. p. 54. ISBN 978-0-443-07145-4.
- ^ "TPCN1 - Two pore calcium channel protein 1 - Homo sapiens (Human) - TPCN1 gene & protein". www.uniprot.org. Retrieved 2017-12-11.
- ^ Gao Z, Ruden DM, Lu X (December 2003). "PKD2 cation channel is required for directional sperm movement and male fertility". Current Biology. 13 (24): 2175–2178. doi:10.1016/j.cub.2003.11.053. PMID 14680633.
- ^ Putney JW, Steinckwich-Besançon N, Numaga-Tomita T, Davis FM, Desai PN, D'Agostin DM, et al. (June 2017). "The functions of store-operated calcium channels". Biochimica et Biophysica Acta (BBA) - Molecular Cell Research. 1864 (6): 900–906. doi:10.1016/j.bbamcr.2016.11.028. PMC 5420336. PMID 27913208.
- ^ Katz AM (September 1986). "Pharmacology and mechanisms of action of calcium-channel blockers". Journal of Clinical Hypertension. 2 (3 Suppl): 28S–37S. PMID 3540226.
- ^ Zamponi GW, Lory P, Perez-Reyes E (July 2010). "Role of voltage-gated calcium channels in epilepsy". Pflügers Archiv. 460 (2): 395–403. doi:10.1007/s00424-009-0772-x. PMC 3312315. PMID 20091047.
External links
- "The Weiss Lab". The Weiss Lab is investigating the molecular and cellular mechanisms underlying human diseases caused by dysfunction of ion channels.
- "Voltage-Gated Ion Channels". IUPHAR Database of Receptors and Ion Channels. International Union of Basic and Clinical Pharmacology.
- . a manually curated database of protein-protein interactions for mammalian TRP channels. Archived from the original on 2016-08-10. Retrieved 2021-06-18.
- Calcium+Channels at the U.S. National Library of Medicine Medical Subject Headings (MeSH)