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This Article Full Text Full Text (PDF) All Versions of this Article: 95/5/3035    most recent 00858.2005v1 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 ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Klassen, T. L. Articles by Spencer, A. N. Search for Related Content PubMed PubMed Citation Articles by Klassen, T. L. Articles by Spencer, A. N.

Atypical Phenotypes From Flatworm Kv3 Channels

¹Department of Biological Sciences, University of Alberta, Edmonton, Alberta; and Bamfield Marine Sciences Centre, Bamfield, British Columbia, Canada; ²Medical Research Council Functional Genetics Unit, Department of Human Anatomy and Genetics, University of Oxford, Oxford, United Kingdom; and ³Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada

Submitted 16 August 2005; accepted in final form 27 January 2006

Divergence of the Shaker superfamily of voltage-gated (Kv) ion channels early in metazoan evolution created numerous electrical phenotypes that were presumably selected to produce a wide range of excitability characteristics in neurons, myocytes, and other cells. A comparative approach that emphasizes this early radiation provides a comprehensive sampling of sequence space that is necessary to develop generally applicable models of the structure–function relationship in the Kv potassium channel family. We have cloned and characterized two Shaw-type potassium channels from a flatworm (Notoplana atomata) that is arguably a representative of early diverging bilaterians. When expressed in Xenopus oocytes, one of these cloned channels, N.at-Kv3.1, exhibits a noninactivating, outward current with slow opening kinetics that are dependent on both the holding potential and the activating potential. A second Shaw-type channel, N.at-Kv3.2, has very different properties, showing weak inward rectification. These results demonstrate that broad phylogenetic sampling of proteins of a single family will reveal unexpected properties that lead to new interpretations of structure–function relationships.