Calcium channel: Information from Answers.com

A Calcium channel is an ion channel which displays selective permeabiltiy 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	Gated by	Protein	Gene	Location	Function
L-type	high voltage	Ca_v1.1 Ca_v1.2 Ca_v1.3 Ca_v1.4	CACNA1S CACNA1C CACNA1D CACNA1F	Skeletal muscle, bone (osteoblasts), ventricular myocytes**, dendrites and dendritic spines of cortical neurones	SMC and cardiac muscle contraction ^[3]. Responsible for prolonged action potential in cardiac muscle.
P-type/Q-type	high voltage	Ca_v2.1	CACNA1A	Purkinje neurons in the cerebellum / Cerebellar granule cells	neurotransmitter release ^[3]
N-type	high voltage	Ca_v2.2	CACNA1B	Throughout the brain	neurotransmitter release ^[3]
R-type	intermediate voltage	Ca_v2.3	CACNA1E	Cerebellar granule cells, other neurons	?^[3]
T-type	low voltage	Ca_v3.1 Ca_v3.2 Ca_v3.3	CACNA1G CACNA1H CACNA1I	neurons, cells that have pacemaker activity, bone (osteocytes)	Regular sinus rhythm^[3]

the receptor-operated calcium channels (in vasoconstriction)
- P2X receptor ^[4]

Type	Gated by	Gene	Location	Function
IP₃ receptor	IP₃		ER/SR	Releases calcium from ER/SR in response to IP₃ by e.g. GPCRs ^[3]
Ryanodine receptor	dihydropyridine receptors in T-tubules and increased intracellular calcium (Calcium Induced Calcium Release - CICR)		ER/SR	Calcium-induced calcium release in myocytes ^[3]
Two-pore channel
Cation channels of sperm
store-operated channels	indirectly by ER/SR depletion of calcium^[3]		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. http://linkinghub.elsevier.com/retrieve/pii/S0955-0674(96)80025-1.
^ ^a ^b ^c ^d ^e ^f ^g ^h Rang, H. P. (2003). Pharmacology. Edinburgh: Churchill Livingstone. ISBN 0-443-07145-4. Page 53
^ Walter F., PhD. Boron (2005). Medical Physiology: A Cellular And Molecular Approach. Elsevier/Saunders. ISBN 1-4160-2328-3. Page 479

"Voltage-Gated Ion Channels". IUPHAR Database of Receptors and Ion Channels. International Union of Basic and Clinical Pharmacology. http://www.iuphar-db.org/IC/ReceptorFamiliesForward.
MeSH Calcium+Channels

Ca²⁺: Calcium channel

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)

Ligand-gated	Inositol triphosphate receptor (1, 2, 3) · Ryanodine receptor (1, 2, 3)

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)

Constitutively active	Epithelial sodium channel (α, β, γ, δ)

Voltage-gated	K_vα1-6 (1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.10) · (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

Calcium-activated	BK channel (α1, β1, β2, β3, β4) · SK channel (SK1, SK2, SK3, SK4) · K_Ca (1.1, 2.1, 2.2, 2.3, 3.1, 4.1, 4.2, 5.1)

Inward-rectifier	K_ir (1.1, 2.1, 2.2, 2.3, 2.4) · 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)

Other


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) · TRPP (1, 2) · TRPV (1, 2, 3, 4, 5, 6)

Cl^-: Chloride channel	ANO1 · Bestrophin (1, 2) · CFTR · CLCA (1, 2, 3, 4) · CLCN (1, 2, 3, 4, 5, 6, 7, KA, KB) · CLIC (1, 2, 3, 4, 5, 6, L1) · CLNS (1A, 1B)

Cyclic nucleotide-gated (FC)	α (1, 2, 3, 4) · β (1, 2, 3) · HCN (1, 2, 3, 4)

Porin	Aquaporin (1, 2, 3, 4, 5, 7, 8, 9) · Voltage-dependent anion channel (1, 2, 3) · General bacterial porin family

General	Ligand-gated ion channel · Voltage-gated ion channel · Stretch-activated ion channel

	see also disorders

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