Functional study of cytoplasmic loops of human skeletal muscle chloride channel, hClC-1

Linlin Ma, Grigori Y. Rychkov, Allan H. Bretag

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6 Citations (Scopus)


The membrane-resident domain of chloride channels and transporters of the CLC family is composed of 18 α-helices (designated A to R) connected sequentially by extracellular and intracellular loops, whose functional characteristics are generally unclear. To study the relevance of the intracellular loops linking helices D and E, F and G, H and I and J and K, alanine-exchange mutagenesis, split channel strategy, GST (glutathione transferase)-pull-down methods and whole-cell patch-clamp recordings were used. We investigated the possible roles of these loops in binding to the cytoplasmic, carboxyl tail (C-tail) of the protein, as well as their physiological roles in channel function. Although other interacting positions are conceivable, our results indicate that there is unlikely to be significant binding between the C-tail and any one of these individual cytoplasmic loops. Particular loops might, however, be essential for some channel characteristics. For example, alanine-exchange mutation of the loop linking helix D to E eliminated channel currents; of the loop linking helix H to I caused a significant shift of the open probability of fast gating (Pof), towards more positive voltages; and of the loop linking helix J to K locked the common gating of hClC-1 open. Therefore, the gating mechanisms of hClC-1 might not only involve the helices and the C-tail, but also involve some of the loops.

Original languageEnglish
Pages (from-to)1402-1409
Number of pages8
JournalInternational Journal of Biochemistry and Cell Biology
Issue number6
Publication statusPublished or Issued - Jun 2009
Externally publishedYes


  • Carboxyl tail
  • Common gating
  • Cytoplasmic loop
  • Interaction
  • hClC-1

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology

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