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The mouse stargazer gene encodes a neuronal Ca2+-channel gamma subunit.

V A Letts, R Felix, G H Biddlecome, J Arikkath, C L Mahaffey, A Valenzuela, F S Bartlett, Y Mori, K P Campbell, W N Frankel

Nat. Genet., 1998 Aug , 19, 340-7

Stargazer mice have spike-wave seizures characteristic of absence epilepsy, with accompanying defects in the cerebellum and inner ear. We describe here a novel gene, Cacng2, whose expression is disrupted in two stargazer alleles. It encodes a 36-kD protein (stargazin) with structural similarity to the gamma subunit of skeletal muscle voltage-gated calcium (Ca2+) channels. Stargazin is brain-specific and, like other neuronal Ca2+-channel subunits, is enriched in synaptic plasma membranes. In vitro, stargazin increases steady-state inactivation of alpha1 class A Ca2+ channels. The anticipated effect in stargazer mutants, inappropriate Ca2+ entry, may contribute to their more pronounced seizure phenotype compared with other mouse absence models with Ca2+-channel defects. The discovery that the stargazer gene encodes a gamma subunit completes the identification of the major subunit types for neuronal Ca2+ channels, namely alpha1, alpha2delta, beta and gamma, providing a new opportunity to understand how these channels function in the mammalian brain and how they may be targeted in the treatment of neuroexcitability disorders.

http://www.ncbi.nlm.nih.gov/pubmed/9697694