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Transmembrane topology of a CLC chloride channel

Item Type:Article
Title:Transmembrane topology of a CLC chloride channel
Creators Name:Schmidt-Rose, T. and Jentsch, T.J.
Abstract:CLC chloride channels form a large and conserved gene family unrelated to other channel proteins. Knowledge of the transmembrane topology of these channels is important for understanding the effects of mutations found in human myotonia and inherited hypercalciuric kidney stone diseases and for the interpretation of structure-function studies. We now systematically study the topology of human ClC-1, a prototype CLC channel that is defective in human myotonia. Using a combination of in vitro glycosylation scanning and protease protection assays, we show that both N and C termini face the cytoplasm and demonstrate the presence of 10 (or less likely 12) transmembrane spans. Difficult regions were additionally tested by inserting cysteines and probing the effect of cysteine-modifying reagents on ClC-1 currents. The results show that D3 crosses the membrane and D4 does not, and that L549 between D11 and D12 is accessible from the outside. Further, since the modification of cysteines introduced between D11 and D12 and at the extracellular end of D3 strongly affect ClC-1 currents, these regions are suggested to be important for ion permeation.
Keywords:Cell Membrane, Chloride Channels, Cysteine, Mutation, Animals, Rabbits
Source:Proceedings of the National Academy of Sciences of the United States of America
ISSN:0027-8424
Publisher:National Academy of Sciences (U.S.A.)
Volume:94
Number:14
Page Range:7633-7638
Date:8 July 1997
Official Publication:http://www.pnas.org/content/94/14/7633.abstract
PubMed:View item in PubMed

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