HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 278, Issue 42, 40890-40898, October 17, 2003

This Article Full Text Full Text (PDF) All Versions of this Article: 278/42/40890    most recent M304235200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Fernandez, F. R. Articles by Turner, R. W. Search for Related Content PubMed PubMed Citation Articles by Fernandez, F. R. Articles by Turner, R. W. Social Bookmarking                      What's this?

Inactivation of Kv3.3 Potassium Channels in Heterologous Expression Systems^*

Fernando R. Fernandez , Ezequiel Morales , Asim J. Rashid , Robert J. Dunn  and Ray W. Turner  ¶

From the Neuroscience Research Group, University of Calgary, Calgary, Alberta T2N 4N1, Canada and the Departments of Neurology and Biology, McGill University, and Center for Research in Neuroscience, Montreal General Hospital, Montreal, Quebec H3G 1A4, Canada

Kv3.3 K⁺ channels are believed to incorporate an NH₂-terminal domain to produce an intermediate rate of inactivation relative to the fast inactivating K⁺ channels Kv3.4 and Kv1.4. The rate of Kv3.3 inactivation has, however, been difficult to establish given problems in obtaining consistent rates of inactivation in expression systems. This study characterized the properties of AptKv3.3, the teleost homologue of Kv3.3, when expressed in Chinese hamster ovary (CHO) or human embryonic kidney (HEK) cells. We show that the properties of AptKv3.3 differ significantly between CHO and HEK cells, with the largest difference occurring in the rate and voltage dependence of inactivation. While AptKv3.3 in CHO cells showed a fast and voltage-dependent rate of inactivation consistent with N-type inactivation, currents in HEK cells showed rates of inactivation that were voltage-independent and more consistent with a slower C-type inactivation. Examination of the mRNA sequence revealed that the first methionine start site had a weak Kozak consensus sequence, suggesting that the lack of inactivation in HEK cells could be due to translation at a second methionine start site downstream of the NH₂-terminal coding region. Mutating the nucleotide sequence surrounding the first methionine start site to one more closely resembling a Kozak consensus sequence produced currents that inactivated with a fast and voltage-dependent rate of inactivation in both CHO and HEK cells. These results indicate that under the appropriate conditions Kv3.3 channels can exhibit fast and reliable inactivation that approaches that more typically expected of "A"-type K⁺ currents.

Received for publication, April 22, 2003 , and in revised form, August 11, 2003.

^* This work was supported by Canadian Institutes of Health Research grants (to R. W. T. and R. J. D.) and an Alberta Heritage Foundation for Medical Research Senior Scholarship (to R. W. T.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

^¶ To whom correspondence should be addressed: Neuroscience Research Group, University of Calgary, 3330 Hospital Dr. N.W., Calgary, Alberta T2N 4N1, Canada. Tel.: 403-220-8452; Fax: 403-283-2700; E-mail: rwturner{at}ucalgary.ca.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				R. K. Finol-Urdaneta, N. Struver, and H. Terlau Molecular and Functional Differences between Heart mKv1.7 Channel Isoforms J. Gen. Physiol., June 26, 2006; 128(1): 133 - 145. [Abstract] [Full Text] [PDF]

				F. R. Fernandez, W. H. Mehaffey, and R. W. Turner Dendritic Na+ Current Inactivation Can Increase Cell Excitability By Delaying a Somatic Depolarizing Afterpotential J Neurophysiol, December 1, 2005; 94(6): 3836 - 3848. [Abstract] [Full Text] [PDF]

				L. K. Bekar, M. E. Loewen, K. Cao, X. Sun, J. Leis, R. Wang, G. W. Forsyth, and W. Walz Complex Expression and Localization of Inactivating Kv Channels in Cultured Hippocampal Astrocytes J Neurophysiol, March 1, 2005; 93(3): 1699 - 1709. [Abstract] [Full Text] [PDF]

				F. R. Fernandez, W. H. Mehaffey, M. L. Molineux, and R. W. Turner High-Threshold K+ Current Increases Gain by Offsetting a Frequency-Dependent Increase in Low-Threshold K+ Current J. Neurosci., January 12, 2005; 25(2): 363 - 371. [Abstract] [Full Text] [PDF]

				T. Shevchenko, R. Teruyama, and W. E. Armstrong High-Threshold, Kv3-Like Potassium Currents in Magnocellular Neurosecretory Neurons and Their Role in Spike Repolarization J Neurophysiol, November 1, 2004; 92(5): 3043 - 3055. [Abstract] [Full Text] [PDF]

				A. Lewis, Z. A. McCrossan, and G. W. Abbott MinK, MiRP1, and MiRP2 Diversify Kv3.1 and Kv3.2 Potassium Channel Gating J. Biol. Chem., February 27, 2004; 279(9): 7884 - 7892. [Abstract] [Full Text] [PDF]