Calcium channel

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A calcium channel is an ion channel which displays selective permeability to calcium ions. It is sometimes synonymous as voltage-dependent 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 neurones
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
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.
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)

Ligand-gated

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. GPCRs4
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 myocytes4
Two-pore channel
Cation channels of sperm
store-operated channels indirectly by ER/SR depletion of calcium4 ORAI1, ORAI2, ORAI3 plasma membrane

Pharmacology

Calcium channel blockers are used to treat hypertension.

References

  1. ^ "calcium channel" at Dorland's Medical Dictionary
  2. ^ Striggow F, Ehrlich BE (August 1996). "Ligand-gated calcium channels inside and out". Curr. Opin. Cell Biol. 8 (4): 490–5. doi:10.1016/S0955-0674(96)80025-1. PMID 8791458. 
  3. ^ Walter F., PhD. Boron (2005). Medical Physiology: A Cellular And Molecular Approach. Elsevier/Saunders. ISBN 1-4160-2328-3.  Page 479
  4. ^ a b c Rang, H. P. (2003). Pharmacology. Edinburgh: Churchill Livingstone. ISBN 0-443-07145-4.  Page 53

External links

  • "Voltage-Gated Ion Channels". IUPHAR Database of Receptors and Ion Channels. International Union of Basic and Clinical Pharmacology. 
  • "TRIP Database". a manually curated database of protein-protein interactions for mammalian TRP channels. 







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