A calcium channel is an ion channel which shows selective permeability to calcium ions. It is sometimes synonymous with voltage-gated calcium channel, which are a type of calcium channel regulated by changes in membrane potential. Some calcium channels are regulated by the binding of a ligand.[1] Other calcium channels can also be regulated by both voltage and ligands to provide precise control over ion flow. Some cation channels allow calcium as well as other cations to pass through the membrane.
Calcium channels can participate in the creation of action potentials across cell membranes. Calcium channels can also be used to release calcium ions as second messengers within the cell, affecting downstream signaling pathways.
Voltage-gated
editMain article: voltage-gated calcium channel
| 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) | 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) | neurons, cells that have pacemaker activity, bone (osteocytes), thalamus (thalamus) |
Ligand-gated
edit| 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 |
| 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 |
| Two-pore channel | Nicotinic acid adenine dinucleotide phosphate (NAADP) | TPCN1, TPCN2 | endosomal/lysosomal membranes | NAADP-activated calcium transport across endosomal/lysosomal membranes |
| Store-operated channels[2] | indirectly by ER/SR depletion of calcium | ORAI1, ORAI2, ORAI3 | plasma membrane | Provides calcium signaling to the cytoplasm |
Other Calcium Permeable Channels:
editThere are several cation channel families that allow calcium and other positively charged ions to pass through. These include P2X receptors, Transient Receptor Potential (TRP) channels, Cyclic nucleotide-gated (CNG) channels, Acid-sensing ion channels, and SOC channels.[3] These channels can be regulated by membrane voltage potentials, ligands, and/or other cellular conditions. Cat-Sper channels, found in mammalian sperm, are one example of this as they are voltage gated and ligand regulated.[4]
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editReferences
edit- ^ Zamponi, Gerald W. (2017-12-20). "A Crash Course in Calcium Channels". ACS Chemical Neuroscience. 8 (12): 2583–2585. doi:10.1021/acschemneuro.7b00415. ISSN 1948-7193.
- ^ Prakriya, Murali; Lewis, Richard S. (2015-09-15). "Store-Operated Calcium Channels". Physiological Reviews. 95 (4): 1383–1436. doi:10.1152/physrev.00020.2014. ISSN 0031-9333. PMC 4600950. PMID 26400989.
{{cite journal}}: CS1 maint: PMC format (link) - ^ Trudeau, Jie Zheng, Matthew C., ed. (2023-06-28). Textbook of Ion Channels Volume II: Properties, Function, and Pharmacology of the Superfamilies. Boca Raton: CRC Press. doi:10.1201/9781003096276/textbook-ion-channels-volume-ii-jie-zheng-matthew-trudeau. ISBN 978-1-003-09627-6.
{{cite book}}: CS1 maint: multiple names: editors list (link) - ^ Wu, Jianping; Yan, Zhen; Li, Zhangqiang; Yan, Chuangye; Lu, Shan; Dong, Mengqiu; Yan, Nieng (2015-12-18). "Structure of the voltage-gated calcium channel Ca v 1.1 complex". Science. 350 (6267). doi:10.1126/science.aad2395. ISSN 0036-8075.