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Cav2.1, also called the P/Qvoltage-dependent calcium channel, is a calcium channel found mainly in the brain.[5] Specifically, it is found on the presynaptic terminals of neurons in the brain and cerebellum.[5] Cav2.1 plays an important role in controlling the release of neurotransmitters between neurons.[5] It is composed of multiple subunits, including alpha-1, beta, alpha-2/delta, and gamma subunits.[6] The alpha-1 subunit is the pore-forming subunit (it is the hole through which the calcium ions flow).[6] Different kinds of calcium channels have different isoforms (versions) of the alpha-1 subunit. Cav2.1 has the alpha-1A subunit,[6] which is encoded by the CACNA1A gene.[5]
Function
"Voltage-dependent calcium channels 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, and gene expression. Calcium channels are multisubunit complexes composed of alpha-1, beta, alpha-2/delta, and gamma subunits. The channel activity is directed by the pore-forming alpha-1 subunit, whereas, the others act as auxiliary subunits regulating this activity. The distinctive properties of the calcium channel types are related primarily to the expression of a variety of alpha-1 isoforms, alpha-1A, B, C, D, E, and S. This gene encodes the alpha-1A subunit, which is predominantly expressed in neuronal tissue."[6]
Clinical significance
Mutations in the CACNA1A gene are associated with multiple neurologic disorders, many of which are episodic, such as familial hemiplegic migraine, movement disorders such as episodic ataxia, and epilepsy with multiple seizure types.[7]
"This gene also exhibits polymorphic variation due to (CAG)n-repeats. Multiple transcript variants encoding different isoforms have been found for this gene. In one set of transcript variants, the (CAG)n-repeats occur in the 3' UTR, and are not associated with any disease. However, in another set of variants, an insertion extends the coding region to include the (CAG)n-repeats which encode a polyglutamine tract. Expansion of the (CAG)n-repeats from the normal 4-16 to 21-28 in the coding region is associated with spinocerebellar ataxia 6."[6]
^Papandreou A, Danti FR, Spaull R, Leuzzi V, Mctague A, Kurian MA (February 2020). "The expanding spectrum of movement disorders in genetic epilepsies". Developmental Medicine and Child Neurology. 62 (2): 178–191. doi:10.1111/dmcn.14407. PMID31784983. S2CID208498567.
Catterall WA, Perez-Reyes E, Snutch TP, Striessnig J (December 2005). "International Union of Pharmacology. XLVIII. Nomenclature and structure-function relationships of voltage-gated calcium channels". Pharmacological Reviews. 57 (4): 411–25. doi:10.1124/pr.57.4.5. PMID16382099. S2CID10386627.
Perez-Reyes E, Castellano A, Kim HS, Bertrand P, Baggstrom E, Lacerda AE, et al. (January 1992). "Cloning and expression of a cardiac/brain beta subunit of the L-type calcium channel". The Journal of Biological Chemistry. 267 (3): 1792–7. PMID1370480.
Joutel A, Bousser MG, Biousse V, Labauge P, Chabriat H, Nibbio A, et al. (September 1993). "A gene for familial hemiplegic migraine maps to chromosome 19". Nature Genetics. 5 (1): 40–5. doi:10.1038/ng0993-40. PMID8220421. S2CID6493091.
Margolis RL, Breschel TS, Li SH, Kidwai AS, Antonarakis SE, McInnis MG, Ross CA (July 1995). "Characterization of cDNA clones containing CCA trinucleotide repeats derived from human brain". Somatic Cell and Molecular Genetics. 21 (4): 279–84. doi:10.1007/BF02255782. PMID8525433. S2CID22174220.
Diriong S, Lory P, Williams ME, Ellis SB, Harpold MM, Taviaux S (December 1995). "Chromosomal localization of the human genes for alpha 1A, alpha 1B, and alpha 1E voltage-dependent Ca2+ channel subunits". Genomics. 30 (3): 605–9. doi:10.1006/geno.1995.1284. PMID8825650.
Ophoff RA, Terwindt GM, Vergouwe MN, van Eijk R, Oefner PJ, Hoffman SM, et al. (November 1996). "Familial hemiplegic migraine and episodic ataxia type-2 are caused by mutations in the Ca2+ channel gene CACNL1A4". Cell. 87 (3): 543–52. doi:10.1016/S0092-8674(00)81373-2. hdl:1765/57576. PMID8898206. S2CID16840573.
Zhuchenko O, Bailey J, Bonnen P, Ashizawa T, Stockton DW, Amos C, et al. (January 1997). "Autosomal dominant cerebellar ataxia (SCA6) associated with small polyglutamine expansions in the alpha 1A-voltage-dependent calcium channel". Nature Genetics. 15 (1): 62–9. doi:10.1038/ng0197-62. PMID8988170. S2CID9116828.
De Waard M, Liu H, Walker D, Scott VE, Gurnett CA, Campbell KP (January 1997). "Direct binding of G-protein betagamma complex to voltage-dependent calcium channels". Nature. 385 (6615): 446–50. doi:10.1038/385446a0. PMID9009193. S2CID4287544.