background:
The receptor for the 1,4-dihydropyrodine (DHPR) class of Ca2+ channel is most abundant in the transverse tubular membranes of skeletal muscle. DHRP is essential in excitation-contraction (E-C) coupling and has been proposed to have a dual function as a calcium channel and voltage sensor. Skeletal muscle DHRP consists of four subunits: alpha1 (170kDa); alpha2 (175kDa non-reduced, 150kDa reduced); beta (52kDa) and gamma (32kDa).
Function:
Voltage-sensitive calcium channels (VSCC) mediate the entry of calcium ions into excitable cells and are also involved in a variety of calcium-dependent processes, including muscle contraction, hormone or neurotransmitter release, gene expression, cell motility, cell division and cell death. The isoform alpha-1C gives rise to L-type calcium currents. Long-lasting (L-type) calcium channels belong to the 'high-voltage activated' (HVA) group. They are blocked by dihydropyridines (DHP), phenylalkylamines, benzothiazepines, and by omega-agatoxin-IIIA (omega-Aga-IIIA). They are however insensitive to omega-conotoxin-GVIA (omega-CTx-GVIA) and omega-agatoxin-IVA (omega-Aga-IVA). Calcium channels containing the alpha-1C subunit play an important role in excitation-contraction coupling in the heart. The various isoforms display marked differences in the sensitivity to DHP compounds. Binding of calmodulin or CABP1 at the same regulatory sites results in an opposit effects on the channel function.
Subunit:
Voltage-dependent calcium channels are multisubunit complexes, consisting of alpha-1, alpha-2, beta and delta subunits in a 1:1:1:1 ratio. The channel activity is directed by the pore-forming and voltage-sensitive alpha-1 subunit. In many cases, this subunit is sufficient to generate voltage-sensitive calcium channel activity. The auxiliary subunits beta and alpha-2/delta linked by a disulfide bridge regulate the channel activity. Interacts with CACNA2D4. Interacts (via the N-terminus and the SLCterminal C and IQ motifs) with CABP1. The binding via the C motif is calcium independent whereas the binding via IQ requires the presence of calcium and is mutually exclusive with calmodulin binding. The binding to the cytoplasmic N-terminal domain is calcium independent but is essential for the channel modulation. Interacts (via SLCterminal CDB motif) with CABP5; in a calcium-dependent manner (By similarity).
Subcellular Location:
Membrane. Cell membrane. The interaction between RRAD and CACNB2 regulates its trafficking to the cell membrane.
Tissue Specificity:
Expressed in brain, heart, jejunum, ovary, pancreatic beta-cells and vascular smooth muscle. Overall expression is reduced in atherosclerotic vascular smooth muscle.
Post-translational modifications:
Phosphorylation by PKA activates the channel.
DISEASE:
Defects in CACNA1C are the cause of Timothy syndrome (TS) [MIM:601005]. TS is a disorder characterized by multiorgan dysfunction including lethal arrhythmias, webbing of fingers and toes, congenital heart disease, immune deficiency, intermittent hypoglycemia, cognitive abnormalities and autism.
Defects in CACNA1C are the cause of Brugada syndrome type 3 (BRGDA3) [MIM:611875]. A heart disease characterized by the association of Brugada syndrome with shortened QT intervals. Brugada syndrome is a tachyarrhythmia characterized by right bundle branch block and ST segment elevation on an electrocardiogram (ECG). It can cause the ventricles to beat so fast that the blood is prevented from circulating efficiently in the body. When this situation occurs (called ventricular fibrillation), the individual will faint and may die in a few minutes if the heart is not reset.
Similarity:
Belongs to the calcium channel alpha-1 subunit (TC 1.A.1.11) family. CACNA1C subfamily.
Database links:
Entrez Gene: 775 Human
Entrez Gene: 12288 Mouse
Entrez Gene: 100144322 Rabbit
Entrez Gene: 24239 Rat
Omim: 114205 Human
SwissProt: Q13936 Human
SwissProt: Q01815 Mouse
SwissProt: P15381 Rabbit
SwissProt: P4402 Rat
Unigene: 118262 Human
Unigene: 436656 Mouse
Unigene: 9827 Rat
Important Note:
This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications.
Involvement in disease; Defects in CACNA1C are the cause of Timothy syndrome (TS) . TS is a disorder characterized by multiorgan dysfunction including lethal arrhythmias, webbing of fingers and toes, congenital heart disease, immune deficiency, intermittent hypoglycemia, cognitive abnormalities and autism.
Defects in CACNA1C are the cause of Brugada syndrome type 3 (BRGDA3). A heart disease characterized by the association of Brugada syndrome with shortened QT intervals. Brugada syndrome is a tachyarrhythmia characterized by right bundle branch block and ST segment elevation on an electrocardiogram (ECG). It can cause the ventricles to beat so fast that the blood is prevented from circulating efficiently in the body. When this situation occurs (called ventricular fibrillation), the individual will faint and may die in a few minutes if the heart is not reset.
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