Click here to close Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly. We suggest using a current version of Chrome, FireFox, or Safari.
XB-ART-40985
J Biol Chem 2010 Mar 19;28512:9077-89. doi: 10.1074/jbc.M109.054940.
Show Gene links Show Anatomy links

Sodium channel carboxyl-terminal residue regulates fast inactivation.

Nguyen HM , Goldin AL .


???displayArticle.abstract???
The Na(v)1.2 and Na(v)1.3 voltage-gated sodium channel isoforms demonstrate distinct differences in their kinetics and voltage dependence of fast inactivation when expressed in Xenopus oocytes. Co-expression of the auxiliary beta1 subunit accelerated inactivation of both the Na(v)1.2 and Na(v)1.3 isoforms, but it did not eliminate the differences, demonstrating that this property is inherent in the alpha subunit. By constructing chimeric channels between Na(v)1.2 and Na(v)1.3, we demonstrate that the carboxyl terminus is responsible for the differences. The Na(v)1.2 carboxyl terminus caused faster inactivation in the Na(v)1.3 backbone, and the Na(v)1.3 carboxyl terminus caused slower inactivation in the Na(v)1.2 channel. Through analysis of truncated channels, we identified a homologous 60-amino acid region within the carboxyl terminus of the Na(v)1.2 and the Na(v)1.3 channels that is responsible for this modulation of fast inactivation. Site-directed replacement of Na(v)1.3 lysine 1826 in this region to its Na(v)1.2 analogue glutamic acid 1880 (K1826E) shifted the voltage dependence of inactivation toward that of Na(v)1.2. The K1826E mutation also accelerated the inactivation kinetics to a level comparable with that of Na(v)1.2. The reverse Na(v)1.2 E1880K mutation exhibited much slower inactivation kinetics and depolarized inactivation voltage dependence. A complementary mutation located within the inactivation linker of Na(v)1.3 (K1453E) caused inactivation changes mirroring those caused by the K1826E mutation in Na(v)1.3. Therefore, we have identified a homologous carboxyl-terminal residue that regulates the kinetics and voltage dependence of fast inactivation in sodium channels, possibly via a charge-dependent interaction with the inactivation linker.

???displayArticle.pubmedLink??? 20089854
???displayArticle.pmcLink??? PMC2838328
???displayArticle.link??? J Biol Chem
???displayArticle.grants??? [+]


References [+] :
Abriel, Novel arrhythmogenic mechanism revealed by a long-QT syndrome mutation in the cardiac Na(+) channel. 2001, Pubmed