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Gene Family: Calcium voltage-gated channel alpha1 subunits (CACNA1)

Voltage-dependent calcium channel: Voltage-dependent calcium channels ( VDCCs ) are a group of voltage-gated ion channels found in the membrane of excitable cells ( e.g., muscle, glial cells, neurons, etc.) with a permeability to the calcium ion Ca 2+. These channels are slightly permeable to sodium ions, so they are also called Ca 2+ -Na + channels, but their permeability to calcium is about 1000-fold greater than to sodium under normal physiological conditions. At physiologic or resting membrane potential, VDCCs are normally closed. They are activated ( i.e., opened) at depolarized membrane potentials and this is the source of the "voltage-dependent" epithet. The concentration of calcium (Ca 2+ ions) is normally several thousand times higher outside of the cell than inside. Activation of particular VDCCs allows Ca 2+ to rush into the cell, which, depending on the cell type, results in activation of calcium-sensitive potassium channels, muscular contraction, excitation of neurons, up-regulation of gene expression, or release of hormones or neurotransmitters. VDCCs have been immunolocalized in the zona glomerulosa of normal and hyperplastic human adrenal, as well as in aldosterone -producing adenomas (APA), and in the latter T-type VDCCs correlated with plasma aldosterone levels of patients. Excessive activation of VDCCs is a major component of excitotoxicity, as severely elevated levels of intracellular calcium activates enzymes which, at high enough levels, can degrade essential cellular structures. [Source: Wikipedia]

Genes contained within the family: 10

Approved Symbol Approved Name Previous Symbols Synonyms Chromosome
CACNA1A calcium voltage-gated channel subunit alpha1 A CACNL1A4, SCA6, MHP1, MHP Cav2.1, EA2, APCA, HPCA, FHM 19p13.13
CACNA1B calcium voltage-gated channel subunit alpha1 B CACNL1A5 Cav2.2, CACNN 9q34.3
CACNA1C calcium voltage-gated channel subunit alpha1 C CCHL1A1, CACNL1A1 Cav1.2, CACH2, CACN2, TS, LQT8 12p13.33
CACNA1D calcium voltage-gated channel subunit alpha1 D CCHL1A2, CACNL1A2 Cav1.3, CACH3, CACN4 3p21.1
CACNA1E calcium voltage-gated channel subunit alpha1 E CACNL1A6 Cav2.3, BII, CACH6 1q25.3
CACNA1F calcium voltage-gated channel subunit alpha1 F CSNB2, AIED Cav1.4, JM8, JMC8, CSNBX2, CORDX3, CSNB2A, OA2 Xp11.23
CACNA1G calcium voltage-gated channel subunit alpha1 G Cav3.1, NBR13 17q21.33
CACNA1H calcium voltage-gated channel subunit alpha1 H Cav3.2 16p13.3
CACNA1I calcium voltage-gated channel subunit alpha1 I Cav3.3 22q13.1
CACNA1S calcium voltage-gated channel subunit alpha1 S HOKPP, MHS5, CACNL1A3 Cav1.1, hypoPP 1q32.1


The α1 subunit pore (~190 kDa in molecular mass) is the primary subunit necessary for channel functioning in the high-voltage-gated calcium channels (HVGCCs), and consists of the characteristic four homologous I–IV domains containing six transmembrane α-helices each. The α1 subunit forms the Ca2+ selective pore, which contains voltage-sensing machinery and the drug/toxin-binding sites. A total of ten α1 subunit genes have been identified in humans.