The voltage-gated potassium channel Kv3.3 is the causative gene of SCA13 (spinocerebellar ataxia type 13), an autosomal dominant neurological disorder. The four dominant mutations identified to date cause Kv3.3 channels to be non-functional or have altered gating properties in Xenopus oocytes. In the present paper, we report that SCA13 mutations affect functional as well as protein expression of Kv3.3 channels in a mammalian cell line. The reduced protein level of SCA13 mutants is caused by a shorter protein half-life, and blocking the ubiquitin–proteasome pathway increases the total protein of SCA13 mutants more than wild-type. SCA13 mutated amino acids are highly conserved, and the side chains of these residues play a critical role in the stable expression of Kv3.3 proteins. In addition, we show that mutant Kv3.3 protein levels could be partially rescued by treatment with the chemical chaperone TMAO (trimethylamine N-oxide) and to a lesser extent with co-expression of Kv3.1b. Thus our results suggest that amino acid side chains of SCA13 positions affect the protein half-life and/or function of Kv3.3, and the adverse effect on protein expression cannot be fully rescued.
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Research Article|
August 09 2013
Spinocerebellar ataxia-13 Kv3.3 potassium channels: arginine-to-histidine mutations affect both functional and protein expression on the cell surface
Jian Zhao;
Jian Zhao
*Department of Biological Sciences and Center for Cancer, Genetic Diseases, and Gene Regulation, Fordham University, Bronx, NY 10458, U.S.A.
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Jing Zhu;
Jing Zhu
*Department of Biological Sciences and Center for Cancer, Genetic Diseases, and Gene Regulation, Fordham University, Bronx, NY 10458, U.S.A.
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William B. Thornhill
William B. Thornhill
1
*Department of Biological Sciences and Center for Cancer, Genetic Diseases, and Gene Regulation, Fordham University, Bronx, NY 10458, U.S.A.
1To whom correspondence should be addressed (email thornhill@fordham.edu).
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Publisher: Portland Press Ltd
Received:
January 04 2013
Revision Received:
May 22 2013
Accepted:
June 05 2013
Accepted Manuscript online:
June 05 2013
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2013 Biochemical Society
2013
Biochem J (2013) 454 (2): 259–265.
Article history
Received:
January 04 2013
Revision Received:
May 22 2013
Accepted:
June 05 2013
Accepted Manuscript online:
June 05 2013
Citation
Jian Zhao, Jing Zhu, William B. Thornhill; Spinocerebellar ataxia-13 Kv3.3 potassium channels: arginine-to-histidine mutations affect both functional and protein expression on the cell surface. Biochem J 1 September 2013; 454 (2): 259–265. doi: https://doi.org/10.1042/BJ20130034
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