L-type calcium channels are composed of five subunits. The protein encoded by this gene represents one of these subunits, gamma, and is one of several gamma subunit proteins. It is an integral membrane protein that is thought to stabilize the calcium channel in an inactive (closed) state. This protein is similar to the mouse stargazin protein, mutations in which having been associated with absence seizures, also known as petit-mal or spike-wave seizures. This gene is a member of the neuronal calcium channel gamma subunit gene subfamily of the PMP-22/EMP/MP20 family.[1]
Stargazin is involved in the transportation of AMPA receptors to the synaptic membrane, and the regulation of their receptor rate constants — via its extracellular domain — once it is there. As it is highly expressed throughout the cerebral cortex, it is likely to have an important role in learning within these areas, due to the importance of AMPA receptors in LTP.
Clinical significance
Disruptions of CACNG2 have been implicated in autism.[2]
↑ 3.03.1Chen L, Chetkovich DM, Petralia RS, Sweeney NT, Kawasaki Y, Wenthold RJ, Bredt DS, Nicoll RA (2000). "Stargazin regulates synaptic targeting of AMPA receptors by two distinct mechanisms". Nature. 408 (6815): 936–43. doi:10.1038/35050030. PMID11140673.
↑Choi J, Ko J, Park E, Lee JR, Yoon J, Lim S, Kim E (Apr 2002). "Phosphorylation of stargazin by protein kinase A regulates its interaction with PSD-95". The Journal of Biological Chemistry. 277 (14): 12359–63. doi:10.1074/jbc.M200528200. PMID11805122.
↑Deng F, Price MG, Davis CF, Mori M, Burgess DL (Jul 2006). "Stargazin and other transmembrane AMPA receptor regulating proteins interact with synaptic scaffolding protein MAGI-2 in brain". The Journal of Neuroscience. 26 (30): 7875–84. doi:10.1523/JNEUROSCI.1851-06.2006. PMID16870733.
Further reading
Powers PA, Liu S, Hogan K, Gregg RG (May 1993). "Molecular characterization of the gene encoding the gamma subunit of the human skeletal muscle 1,4-dihydropyridine-sensitive Ca2+ channel (CACNLG), cDNA sequence, gene structure, and chromosomal location". The Journal of Biological Chemistry. 268 (13): 9275–9. PMID8387489.
Black JL, Lennon VA (Apr 1999). "Identification and cloning of putative human neuronal voltage-gated calcium channel gamma-2 and gamma-3 subunits: neurologic implications". Mayo Clinic Proceedings. 74 (4): 357–61. doi:10.4065/74.4.357. PMID10221464.
Burgess DL, Matsuura T, Ashizawa T, Noebels JL (Jan 2000). "Genetic localization of the Ca2+ channel gene CACNG2 near SCA10 on chromosome 22q13". Epilepsia. 41 (1): 24–7. doi:10.1111/j.1528-1157.2000.tb01500.x. PMID10643919.
Chen L, Chetkovich DM, Petralia RS, Sweeney NT, Kawasaki Y, Wenthold RJ, Bredt DS, Nicoll RA (2001). "Stargazin regulates synaptic targeting of AMPA receptors by two distinct mechanisms". Nature. 408 (6815): 936–43. doi:10.1038/35050030. PMID11140673.
Burgess DL, Gefrides LA, Foreman PJ, Noebels JL (Feb 2001). "A cluster of three novel Ca2+ channel gamma subunit genes on chromosome 19q13.4: evolution and expression profile of the gamma subunit gene family". Genomics. 71 (3): 339–50. doi:10.1006/geno.2000.6440. PMID11170751.
Choi J, Ko J, Park E, Lee JR, Yoon J, Lim S, Kim E (Apr 2002). "Phosphorylation of stargazin by protein kinase A regulates its interaction with PSD-95". The Journal of Biological Chemistry. 277 (14): 12359–63. doi:10.1074/jbc.M200528200. PMID11805122.
Yamazaki M, Ohno-Shosaku T, Fukaya M, Kano M, Watanabe M, Sakimura K (Dec 2004). "A novel action of stargazin as an enhancer of AMPA receptor activity". Neuroscience Research. 50 (4): 369–74. doi:10.1016/j.neures.2004.10.002. PMID15567474.
Priel A, Kolleker A, Ayalon G, Gillor M, Osten P, Stern-Bach Y (Mar 2005). "Stargazin reduces desensitization and slows deactivation of the AMPA-type glutamate receptors". The Journal of Neuroscience. 25 (10): 2682–6. doi:10.1523/JNEUROSCI.4834-04.2005. PMID15758178.
Bedoukian MA, Weeks AM, Partin KM (Aug 2006). "Different domains of the AMPA receptor direct stargazin-mediated trafficking and stargazin-mediated modulation of kinetics". The Journal of Biological Chemistry. 281 (33): 23908–21. doi:10.1074/jbc.M600679200. PMID16793768.
Körber C, Werner M, Hoffmann J, Sager C, Tietze M, Schmid SM, Kott S, Hollmann M (Jun 2007). "Stargazin interaction with alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptors is critically dependent on the amino acid at the narrow constriction of the ion channel". The Journal of Biological Chemistry. 282 (26): 18758–66. doi:10.1074/jbc.M611182200. PMID17483093.