Calcium channel

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.

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)	Ca_v1.1 (CACNA1S) Ca_v1.2 (CACNA1C) Ca_v1.3 (CACNA1D) Ca_v1.4 (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)	Ca_v2.1 (CACNA1A)	α₂δ, β, possibly γ	Purkinje neurons in the cerebellum / Cerebellar granule cells
N-type calcium channel ("Neural"/"Non-L")	HVA (high-voltage-activated)	Ca_v2.2 (CACNA1B)	α₂δ/β₁, β₃, β₄, possibly γ	Throughout the brain and peripheral nervous system.
R-type calcium channel ("Residual")	intermediate-voltage-activated	Ca_v2.3 (CACNA1E)	α₂δ, β, possibly γ	Cerebellar granule cells, other neurons
T-type calcium channel ("Transient")	low-voltage-activated	Ca_v3.1 (CACNA1G) Ca_v3.2 (CACNA1H) Ca_v3.3 (CACNA1I)		neurons, cells that have pacemaker activity, bone (osteocytes), thalamus (thalamus)

the receptor-operated calcium channels (in vasoconstriction)
- P2X receptor^[3]

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
Cation channels of sperm
store-operated channels	indirectly by ER/SR depletion of calcium^[4]	ORAI1, ORAI2, ORAI3	plasma membrane

↑ "calcium channel" at Dorland's Medical Dictionary
↑ 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.
↑ Walter F., PhD. Boron (2005). Medical Physiology: A Cellular And Molecular Approach. Elsevier/Saunders. ISBN 1-4160-2328-3. Page 479
↑ 4.0 4.1 4.2 Rang, H. P. (2003). Pharmacology. Edinburgh: Churchill Livingstone. ISBN 0-443-07145-4. Page 53

"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.

Calcium Channels at the US National Library of Medicine Medical Subject Headings (MeSH)

Ligand-gated	Inositol trisphosphate receptor 1 2 3 Ryanodine receptor 1 2 3

Voltage-gated	L-type/Ca_vα 1.1 1.2 1.3 1.4 N-type/Ca_vα2.2 P-type/Ca_vα 2.1 Q-type/Ca_vα2.1 R-type/Ca_vα2.3 T-type/Ca_vα 3.1 3.2 3.3 α₂δ-subunits 1 2 β-subunits β1 β2 β3 β4 γ-subunits γ1 γ2 γ3 γ4 Cation channels of sperm 1 2 3 4 Two-pore channel 1 2

Constitutively active	Epithelial sodium channel α β γ δ

Proton-gated	Amiloride-sensitive cation channel 1 2 3 4

Voltage-gated	Na_vα 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 7A Na_vβ 1 2 3 4

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

Index of cells

Description	Structure nucleus chromosome genetics Organelles peroxisome cytoskeleton centrosome epithelia cilia mitochondria Membranes proteins cell adhesions Membrane transport ion channels vesicular transport solute carrier ABC transporters ATPase oxidoreduction-driven

Disease	Structural peroxisome cytoskeleton cilia mitochondria nucleus scleroprotein Membrane channelopathy solute carrier ATPase ABC transporters other extracellular ligands cell surface receptors intracellular signalling Vesicular transport Pore-forming toxins